Iman Islam - Pre-Final

Green Roofs - A Sustainable Approach for Healthier Cities

The Architect Guideline for Green Roof Design in Hot Arid Climates

By Iman Islam AY 2019-2020

2

3

A Guideline document submitted in partial fulfilment of the requirements for the degree of Master of Architecture

The Architect Guideline for Green Roof Design in Hot Arid Climates By Iman Islam

Supervisor Dr. Mostafa Sabbagh

Master of Architecture Program Dar Al-Hekma University 2019-2020

4

TABLE OF CONTENTS LIST OF FIGURES……………..………………………………………..………....…..6 LIST OF TABLES.…………………….……………………..…………..………....…...8

01 CHAPTER I: INTRODUCTION 1.1 Guide Aim…………………….…………………………..………………...……………10 1.2 Who is this guidance for…………………….……………………………..….………....10 1.3 What are Green Roofs…………………….……………………………..…………..…...11 1.4 Green Roofs Known Benefits………………...…………..……………………….….….12

2

CHAPTER II: WATER RESOURCE MANAGEMENT FOR GREEN ROOFS 2.1 Challenges and Opportunities..………………...…………..………………………...…..15 2.2 Strategies for Water Resources..………………...…………..……………………..….....15 2.3 Strategies and Techniques for Irrigation System………...………..….....………….……24

3

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY 3.1 Regulations………………...…………..…………………………………………….…..29 3.2 Types……………………………..…………...…………..……………………….……..41 3.3 Systems………………...…………..………………………………………………...…..49 3.4 Layers………………...…………..………………………………………………….…..50 3.5 Structural Design Considerations………………...…………..………………….…...….60 3.6 Design Consideration and Components………………...………….….…………….......63 3.7 Plant Selection………………...…………..……………………………………………..80 3.8 Installation………………...…………..……………………..…………………………..89 3.9 Maintenance………………...............................…………..……………..……...…..…..94

04 CHAPTER IV: GREEN ROOFS AS A SOCIAL HUB 4.1 Social Life………………...…………..………………………………………….....…...99 4.2 Activity Areas………………...…………..…………………………..……………...….100 4.3 Community Gardening Space………………...…………..……………………...….…..101

CONCLUSION………………...…………..……………………………………….…..107 GLOSSARY………………...…………..……………………………………....…….....109 REFERENCES………………...…………..…………….………………………...…...112 TABLE OF CONTENT

5

LIST OF FIGURES Figure 1: Residential Water Consumption…………………………………………….………..15 Figure 2: Greywater System Diagram…………………………………….………….........…...16 Figure 3: Watering The Green Roof Using Recycled Greywater…..………………….…....…17 Figure 4: Direct A/C Water Use for Irrigation……………………...………….………….……18 Figure 5: In-Direct A/C Water Use for Irrigation…..………………………………….…….…18 Figure 6: Harvesting Rainwater Process…………………………..…………….…………..…20 Figure 7: Tray to Collect Excess Water………………………...…..………………...….......…21 Figure 8: Tray Details: System Which Controls Excess Water Flow System………….......…..22 Figure 9: Excess Water Drainage…………………………………………………….....………22 Figure 10: Excess System Diagram…………………………………………………….………23 Figure 11: Excess Water Harvesting Process……………………………………………...……23 Figure 12: Low-Rise Building: Green Roof Area Required………………………….…….…..38 Figure 13: Mid-Rise Building: Green Roof Area Required………………………….………...39 Figure 14: High-Rise Building: Green Roof Area Required……………………….…….…….40 Figure 15: Types of Green Roofs…………………………………………………….…….…..41 Figure 16: Intensive Green Roof Layers………………………………………………….……45 Figure 17: Extensive Green Roof Layers………………………………………….…………...45 Figure 18: Green Roof Types Components………………………....……….…………………47 Figure 19: Modular and Hybrid Systems Details……………………...………………….……48 Figure 20: Green Roof Layers…………………………………………….………...........…….50 Figure 21: Roof Deck…………………………………………………………...…….……..…50 Figure 22: Waterproofing Membrane……………………………………………………….….51 Figure 23: Fluid Applied Rubberized Asphalt Membrane…………………………….…….….51 Figure 24: Membrane Protection Layer………………………………………………….…..…52 Figure 25: Protection Sheets…………………………………………………………….…...…52 Figure 26: Root Barrier Layer……………………………………………………………….....53 Figure 27: Drainage Layer………………………………………………………………….…..54 Figure 28: Gravel Layer………………………………………………………………………..54 Figure 29: Plastic Layer………………………………………………………………………..54 Figure 30: Combined Drainage………………………………………………………….……..54 Figure 31: Moisture Retention Layer………………………………………………..…………55 Figure 32: Waffle Board…………………………………………………………...…………...55 Figure 33: Filter Fabric Layer………………………………………………………..……...…56 Figure 34: Growing Media Layer…………………………………………………………..…..56 Figure 35: Plants Layer…………………………………………..………...……….…………..57 6

LIST OF FIGURES

LIST OF FIGURES Figure 36: Pre-Planted Modules…………………………………………………..……..……..58 Figure 37: Drip System…………………………………………………………………………58 Figure 38: Subsurface System……………………………………………………………...…..58 Figure 39: Green Roofs Structural Design………………………………………………….….60 Figure 40: Sloped Green Roof…………………………………………………………….……67 Figure 41: Sloped Green Roof Basic Components………………………………………..……67 Figure 42: Sun Exposure on Green Roofs………………………………………………...……70 Figure 43: Examples of Green Roofs Shading Devices………………………………..………71 Figure 44: Solar System Acting as s Shading Element………………………………......…….71 Figure 45: Green Roof Shading System Combined with other Functions……………..………72 Figure 46: Bio-Solar Green Roofs…………………………………………………………...…73 Figure 47: Green Roof Lighting…………………………………………………………….….74 Figure 48: Walkways and Paths on Green Roofs………………………………………….…..76 Figure 49: Walkways and Drains on Green Roofs………………………………………...…..76 Figure 50: Walkways and Paths on Green Roofs………………………………………….…..77 Figure 51: Paths and Walkways Lighting…………………………………………………..…..77 Figure 52: Green Roof Seating Elements…………………………………………………...….78 Figure 53: Water Pond on a Green Roof………………………………………………….……79 Figure 54: Green Roofs Railings and Screens………………………………………………....79 Figure 55: Site Preparation……………………………………………………………….….…91 Figure 56: Waterproof Membrane…………………………………………………….……..…91 Figure 57: Laying the Protection Layers……………………………………………………….91 Figure 58: Protection Sheets, Filter Sheets and Root Stopping………………………….......…91 Figure 59: Installing The Drainage Layer………………………………………………......….92 Figure 60: Soil Layer…………………………………………………………………………...92 Figure 61: Applying Irrigation System: Drip System or Sprinkler System…………………....92 Figure 62: Built-up System……………………………………………………………………..92 Figure 63: Roll-out System……………………………………………………………………..93 Figure 64: Modular System………………………………………………………..……….…..93 Figure 65: Plants Watering Step…………………………………………………………….….93 Figure 66: Shading System………………………………………………………………….….93 Figure 67: Green Roof Maintenance……………………………………………………….......94 Figure 68: Maintenance Schedule……………………………………………………….......…96 Figure 69: Maintenance Schedule...............................................................................................97 Figure 70: Using Green Roofs for Different Activities………………………………….……100 LIST OF FIGURES

7

LIST OF TABLES

Table 1: Irrigation Main Methods…………………………………………………………….24 Table 2: Irrigation Methods Categories………………………………………………………25 Table 3: Green Roofs Codes and Standards………………………………………………..…37 Table 4: A Comparison Between Green Roof Types………………………………………...46 Table 5: Green Roof Systems………………………………………………………………...49 Table 6: Wind Protection Specification………………………………………………………61 Table 7: Green Roofs Considerations………………………………………………………..63 Table 8: Some of the Most Suitable Planets for Hot Arid Climates………………………....81

8

LIST OF TABLES

INTRODUCTION ‘‘INTRODUCTION,, 1.1 Guide Aim 1.2 Who is this Guidance for 1.3 What are Green Roofs 1.4 Green Roofs Known Benefits

CHAPTER I: INTRODUCTION

,, 1.1 Guide Aim The aim of this guide is to provide information on the application of green roofs and contains a set of recommendations towards their successful implementation. It includes standards that apply to green roof design, system components, irrigation systems, installation and maintenance. The context of this guide and the recommendations is for hot arid climates.

1.2 Who is this Guidance for This guide is intended to provide assistance to users, designers, developers, planners, architects, contractors and to whoever is interested in applying green roofs on their constructions.

‘‘ 10

INTRODUCTION

INTRODUCTION 1.3 What is a Green Roof?

A green roof is the rooftop of the building that is partially or completely planted with vegetation and a grown medium, planted over a waterproof membrane.

Architects, and urban planners have become well-aware of the advantages of sustainable development, spurring the recent popularity of green roofs, which are increasingly being incorporated into both existing and new construction sites.

It a way to add a surface and provide usable open space without taking up additional land.

Green roof systems are suitable for all types of buildings either industrial, commercial or domestic building which have either flat or sloped roofs up to a gradient of 50 degrees. It can be applied on either retrofit building or to a new construction.

The severity of environmental changes in recent years has rendered the existence of green roofs all the more crucial.

The insulating effect of green roofs and its ability to prevent loss of heat, also means less consumption of electricity, making it a win-win scenario for both the climate and national budgets.

Green roofs reduce stormwater run-off and lower cooling costs, are both space and cost-effective. Private businesses and municipalities alike are investing in these structures owing to their numerous benefits.

They have several layers of soil and drainage systems in order to allow the plants to grow more efficiently.

Sedum plants are often used due to their ability to weather storms and adaptability to poor quality soil and flat surfaces.

1.4 Green Roofs known Benefits

Social Benefits

• • • • • • •

Leisure and Open Space Visual Aesthetic Beauty Noise Reduction Enhancing Thermal Comfort Increases the Feeling of Well-being Food production Ground for social interactions

Environmental Benefits

• • • • • • •

Air Filtration Binds Dust and Toxic Particles Improves the Microclimate Protection from Solar Radiation Reducing Carbon Footprint Reducing Sulfur Dioxide Footprint Urban Heat Island Reduction

Economical Benefits

• • • •

Energy Saving Cooling Performance on the Building and Surroundings Water Management Increase Property Value Increased Roof Life The Cost of Green Roofs

‘‘

‘‘

• •

INTRODUCTION

11

Benefits

CHAPTER I: INTRODUCTION

Air Filtration

I

Green rooftop plants have the ability to filter out impurities in the air and convert carbon dioxide (CO2) to oxygen (O2), which is the essence of all life. The impurities settle on plant surfaces. While plants absorb gaseous pollutants, particles are broken down by microbes in the soil.

Improves the Microclimate Green roofs cool and humidify the surrounding air. They contribute to improving the microclimate in urban cities.

This cooling process effects significantly and increases the performance of air-conditioning systems and reducing carbon emissions.

Bind Dust and Toxic Particles Green roof vegetation helps to filter out dust and smog particles. Plants absorb nitrates and other harmful materials in the air and rainfall by filtering out pollutants and heavy metals. The latter helps improve local air quality.

Noise Reduction The hard surfaces of urban areas reflect sound rather than absorb it, and roofs are no different. Green roofs, however, can absorb sound, with the substrate tending to block higher sound frequencies, and the vegetation managing to block lower frequencies.

Images Source: (https://land8.com/6-ecological-benefits-of-green-roofs/)

12

INTRODUCTION

Benefits

Benefits

CHAPTER I: INTRODUCTION

Energy Saving Energy-saving and run-off reduction; green roofs can reduce the high-temperature heat in the cities, especially during summer months, which helps in cutting the electricity demand. During winter, green roofs decrease insulation and provide heat. They also help in sewage protection and pollution, which is a serious issue.

Leisure and Open Space In a dense urban environment with limited areas of ground level, applying a green roof on the rooftop provides urban dwellers with the amenity and recreational space, which is essential for healthy living. Green roofs add to the richness of experience and quality of life. They offer opportunities for social interaction between neighbours.

Visual Aesthetic Beauty A green roof helps to improve the beauty of buildings, the visual and environmental diversity that can have positive impacts. Applying a layer of plants on top of the building can enhance the building design and look. They can increase the aesthetic character of both buildings and neighbourhoods.

Urban Heat Island Reduction Green roofs are one of the best mitigation plans for heat transfers since they ensure there is a more significant improvement of thermal comfort. They are not only working on the reduction of direct entry and diffusion of radiation on the roof but improve the lifetime of the roof through the modification of temperature fluctuations.

Images Source: (https://land8.com/6-ecological-benefits-of-green-roofs/)

INTRODUCTION

13

I

WATER RESOURCE ‘‘WATER RESOURCE MANAGEMENT MANAGEMENT FOR ROOFS FOR GREEN GREEN ROOFS,, 2.1 Challenges and Opportunities 2.2 Strategies for Water Resources 2.3 Strategies and Techniques for Irrigation System

2.1 Challenges and Opportunities Lack of rainfall is a major problem in hot arid climates. Water is provided almost for free to residential users, and there is an expansion of wastewater. So, in order to overcome the water scarcity, considerable investments have been undertaken in wastewater treatment.

Treated water can be reused for many purposes, such as watering plants and a source of irrigation of urban green spaces. There are a lot of beneficial, sustainable solutions for water scarcity challenge such utilize the proper disposal of the wastewater and recycle it as greywater, harvesting condensed water from an A/C unit since there is a heavily dependent on AC units in hot climates and harvesting rainwater and excess water from irrigation.

Greywater

CHAPTER II: WATER RESOURCE MANAGEMENT FOR GREEN ROOFS

II 2.2 Strategies for Water Resources Greywater Greywater can be defined as any domestic wastewater produced excluding sewage. In urban water distribution (Figure 1), 56% is used for residential purposes, almost 30% is used to flush toilets. With proper treatment, greywater can be reused for many purposes such as to irrigate both food and non-food producing plants.

5% 10% 35% 20%

30% Shower and Baths

Toilet Flushing

Laundry

Kitchen

Cleaning

Figure 1: Residential Water Consumption Modified by the author, data source: Water Research Foundation, Residential End Uses of Water, 2020

The nutrients in the greywater (such as phosphorus and nitrogen) provide an excellent food source for these plants. In addition, greywater can save almost 70 liters of potable water per person/day in domestic households.

WATER RESOURCE MANAGEMENT FOR GREEN ROOFS

15

II

How Does Greywater System Work Greywater will be collected from the pipes (Figure 2) into the surge tank. Once it is collected inside the tank, the greywater passes through a pre-filter, which will remove any particles. Then water moves to a tank chamber. A mechanical valve in the header of the tank automatically pumps the water into pipes that have the openings to allow the watering process to begin. The process is a closed-up process. The watering process can be either impeded process or shallow process.

Domestic Uses

Greywater

CHAPTER II: WATER RESOURCE MANAGEMENT FOR GREEN ROOFS

Kitchen Sink Laundry Tap

Greywater

Filter

Urban Use Watering /Irrigation

Gardens Green Roof

Shower

Treatments for Re-domestic uses Toilet Flushing Floor Washing Car Washing Figure 2: Greywater System Diagram

Greywater System Components • Hose

• Filters

• Diverter valve

• Pump

• Surge tank The system components are assembled to each other by having the greywater pipes connected to the surge tank. Inside the tank, filters are located to filter the passing through greywater from any particles. A valve in the header of the tank will pump the filtered water into pipes with hoses to allow the watering process to begin.

16

WATER RESOURCE MANAGEMENT FOR GREEN ROOFS

Direct Use Systems For Watering Plants Untreated greywater must be used immediately since bacteria present in the water feed on any organic matter present and multiply very quickly. Using greywater is simple, either syphon it directly from the bath or sink or can fit to a valve to the external waste pipe allowing directing the water to a water butt, so it can be used as needed to water the green roof (Figure 3).

Greywater

CHAPTER II: WATER RESOURCE MANAGEMENT FOR GREEN ROOFS

II

Figure 3: Watering The Green Roof Using Recycled Greywater Modified by the author, images source: (https://www.archdaily.com/farmingkindergarten-vo-trong-nghia-architects-enviromental-strategies)

Greywater Guidelines • Greywater should not be stored for more than 24 hours without treatment. If the greywater is stored for too long, the nutrients will begin to break down and the water will emit an unpleasant odor.

• Minimize contact with greywater. It is advised to use greywater only to water flowers and plants, not vegetables, which will potentially get ingested.

• Infiltrate greywater into the ground, don’t allow it to pool up or runoff. Pooling greywater can provide mosquito breeding grounds.

• Keep your greywater system simple.

WATER RESOURCE MANAGEMENT FOR GREEN ROOFS

17

Harvesting A/C Water

CHAPTER II: WATER RESOURCE MANAGEMENT FOR GREEN ROOFS

Water Harvesting : 1-Harvesting A/C Condensed Water Another sustainable way to water plants is recycling of condensed water from an air conditioning unit. The AC water contains no chlorine, salt, or other chemicals that can be used safely for many purposes, excluding drinking. There are two ways to harvest the A/C water: direct way (Figure 4) and in-direct way (Figure 5).

II

Figure 4: Direct A/C Water Use for Irrigation Source: (https://twitter.com/daleljeddah/status.ac-water.jpg)

Figure 5: In-Direct A/C Water Use for Irrigation Source: (https://twitter.com/daleljeddah/status.ac-water.jpg)

18

WATER RESOURCE MANAGEMENT FOR GREEN ROOFS

Harvesting A/C Water

CHAPTER II: WATER RESOURCE MANAGEMENT FOR GREEN ROOFS

How Does The Direct System Work Water forms when the unit cools warm air, which creates condensation, and it produces water as part of the cooling process. AC unit contains a coil that cools the warm air and causes moisture on the reel. Moisture on the coil slowly flows to outside through a drainpipe. Mostly the water dropping from the AC is collected and used for many purposes, and one of them is watering plants since it can't be used for domestic purposes.

A/C Unit

II

How Does The In-Direct System Work Water forms when the unit cools warm air, which creates condensation, and it produces water as part of the cooling process. Coils will cool the warm air and cause moisture. Moisture will be gathered in the tank in water form. A/C water will be collected from the attached pipes into a tank. Once it is collected inside the tank a mechanical valve in the header of the tank automatically pumps the water into pipes that have the openings to allow the watering process to begin. The process is a closed-up process. The watering process can be either impeded process or shallow process.

Split Unit

Tank

Valve

WATER RESOURCE MANAGEMENT FOR GREEN ROOFS

19

Harvesting Rainwater

CHAPTER II: WATER RESOURCE MANAGEMENT FOR GREEN ROOFS

2-Harvesting Rainwater Rainwater harvesting represents an alternative water supply that captures and stores rainwater for later use. It is as simple as collecting water from surfaces on which rain falls, and subsequently storing this water for later use.

In Green roof technology: Rainwater captured from green roofs is usually used for flushing toilets, irrigation, and for other non-potable purposes.

II

Figure 6: Harvesting Rainwater Process Modified by the author, image source: (http://www.giset.in/AwarenessProgram/Awareness_Program_on)

How Does The System Work Rainwater flows from the roof to filters where dirt particles and debris are separated from the water. Rainwater will be channelled to the tank by pipes to the water storing container. By using pumps, recycled rainwater will be pumped to irrigation system pipes to be reused for green roof watering process (Figure 6).

Note: This system even though with limited raining seasons in hot arid climates will help in harvesting the excess water from the irrigation process to reuse it again for watering plants.

20

WATER RESOURCE MANAGEMENT FOR GREEN ROOFS

3-Harvesting Excess Water Excess water harvesting represents another alternative water supply that collects and stores excess water for later use. The excess water after the rain or irrigation process can be harvested from plants and reused again for irrigation by using trays (Figure 7 and Figure 8) under the vegetation layer.

Excess Water

CHAPTER II: WATER RESOURCE MANAGEMENT FOR GREEN ROOFS

II

Figure 7: Tray to Collect Excess Water Source: (http://www.vegetalid.us/green-roof-technical-resources/extensive-green-roof-design-guide.html)

WATER RESOURCE MANAGEMENT FOR GREEN ROOFS

21

Excess Water

CHAPTER II: WATER RESOURCE MANAGEMENT FOR GREEN ROOFS

II Figure 8: Tray Details: System Which Controls Excess Water Flow System Source: (http://www.vegetalid.us/green-roof-technical-resources/extensive-green-roof-design-guide.html)

How Does The System Work The excess water that is collected into the tray, runs out from the small hose that is located below the tray to the drainage opening (Figure 9), under the drainage opening there is a filter that will collect the dirt particles and debris are separated from the water.

The water will be channelled to the tank by pipes to the water storing container. By using pumps, recycled water will be pumped to irrigation system pipes to be reused for green roof watering process (Figure 10 and Figure 11).

Figure 9: Excess Water Drainage Modified by the author, image source: (http://www.vegetalid.us/green-roof-technicalresources/extensive-green-roof-design-guide.html)

22

WATER RESOURCE MANAGEMENT FOR GREEN ROOFS

Excess Water

Water Tray

Filter

Tank

Pumps

Green Roof Irrigation

Excess Water

Excess Water Harvesting Process

CHAPTER II: WATER RESOURCE MANAGEMENT FOR GREEN ROOFS

Figure 10: Excess System Diagram

II

Figure 118: Excess System Diagram (created by author)

• Controlled excess water flow system form rainwater or irrigation system.

• Healthy plants with increased drought resistance.

• This system is flexible for any design.

Figure 11: Excess Water Harvesting Process Modified by the author, images source: (http://www.vegetalid.us/green-roof-technicalresources/extensive-green-roof-design-guide.html)

WATER RESOURCE MANAGEMENT FOR GREEN ROOFS

23

Irrigation Methods

CHAPTER II: WATER RESOURCE MANAGEMENT FOR GREEN ROOFS

2.3 Strategies and Techniques for Irrigation System Urban Watering can be done manually or by an automated system which is generally the best option. Automatic System is to be installed on a green roof, consider a system that incorporates a rain sensor that shuts off the system in the event of rainfall. This removes the risk that the roof loading may be compromised if the irrigation system is running during raining. Automatic systems require regular physical checks and operation tests. In addition, moisture sensors are used to estimate moisture content in the soil.

Irrigation Methods

II

Green roofs irrigation methods can be classified into sprinkle based or a drip based solutions for water distribution. Each method has different categories under (Table 1).

Table 1: Irrigation Main Methods Drip System

Sprinkle System

Shaped Area Medium Barely visible after the growth

Large Area Low Visible

Watering System

Flow Rate Watering Duration Area Maintenance Visibility

Example

24

WATER RESOURCE MANAGEMENT FOR GREEN ROOFS

Table 2: Irrigation Methods Categories Method

MicroSpray or Sprinkler Irrigation

Surface Drippers or Perforated Pipes

Subsurface Drippers/ Perforated Pipes

Image

Advantages • Low Cost • Visible • Easy to Install • Reliable

Disadvantages

Usage

• Uneven Distribution (Plant Interception) • High Water Loss

• Used for residential, industrial, and agricultural usage.

• It is useful on uneven land.

• Low Cost • Can be buried or fully visible on the surface • Even delivery of water

• Moderate Water Loss

• Drippers are used for lowpressure and low-volume watering such as for lawns and gardens.

• Low Cost • Moderate Efficiency (water delivery to root zone)

• Non Visible (difficult for maintenance) • Higher potential for damage by people digging

• The system is placed below the ground and near to the plant root zone area.

• Used in agriculture or any cultural practice.

WATER RESOURCE MANAGEMENT FOR GREEN ROOFS

25

Irrigation Methods

CHAPTER II: WATER RESOURCE MANAGEMENT FOR GREEN ROOFS

II

Irrigation Methods

CHAPTER II: WATER RESOURCE MANAGEMENT FOR GREEN ROOFS

Method

Subsurface Capillary

Image

Advantages

Disadvantages

Usage

• High Efficiency • Very effective • Transports the water directly to the roots

• High Cost • Maintenance and repair is difficult because not visible • Rise of substrate needed or water will not reach plants

• The system is placed below the ground.

• Used in agriculture or any cultural practice.

• High Efficiency • Ease of Installation

• Rise of substrate needed • This may be unsuitable for plant establishment if the water is applied too deep for the plant roots to reach

• Used in urban farming and agriculture.

• Double productivity and saving 80-90% of the water.

• Good for domestic application for easily accessed

• Cost (requires someone to be present on-site) • Low Water Efficiency • Foliage Wetting • Uneven Distribution

• Used in urban farm irrigation, gardens and sometimes for agricultural purposes.

II

Wicking Associated With Irrigation in Drainage Layer

Hose

26

WATER RESOURCE MANAGEMENT FOR GREEN ROOFS

Irrigation Requirements The use of these Standards is intended to encourage efficient and responsible water management and result in irrigation systems that are practical, and sustainable.

• All existing sprinklers and spray heads shall be removed.

• Micro-sprays not exceeding thirty gallons per hour (30 gph) may be used on areas solely dedicated to edible plants.

Requirements

CHAPTER II: WATER RESOURCE MANAGEMENT FOR GREEN ROOFS

• Hoses used for irrigation shall be equipped with an automated, shut off nozzle.

• Drip irrigation must be on separate valves.

II

• Trees shall be irrigated on a separate valve unless the tree is located in a planter.

• Greywater irrigation systems should be considered.

• Root vegetables shall not be irrigated with greywater.

• Alternate water supply irrigation systems must be considered to save water loss.

• A master shut-off valve is required for all automatic irrigation systems except in systems that make use of technologies that allow for leak detection.

Design Considerations for Irrigation System • Using non-drought tolerant plants or native plants will generally require a permanent irrigation system.

• For heat island reduction intent, an irrigation system will be recommended to increase the evapotranspiration of the plants and cool down the temperature.

• For highly visible green roofs, irrigation is recommended to increase the aesthetic quality of the plants.

• When designing a green roof, there should always be water access on the roof to hook-up during drought periods.

WATER RESOURCE MANAGEMENT FOR GREEN ROOFS

27

GREEN AND ‘‘GREENROOFS ROOFSCONSTRUCTION CONSTRUCTION AND ASSEMBLY ASSEMBLY,, 3.1 Regulations 3.2 Types 3.3 Systems 3.4 Layers 3.5 Structural Design Considerations 3.6 Design Consideration and Components 3.7 Plant Selection 3.8 Installation 3.9 Maintenance

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

3.1 Regulations Landscaped Roofs When roofs are to be vegetated, the live load in the landscaped area shall be 20 psf (0.958 kN/ m²). The weight of the landscaping materials shall be considered dead load.

• As with all roofs, and especially flat roofs, maintenance is required and access must be considered. All green roofs require some amount of maintenance. Therefore it is important to design for ease of access to all types of green roofs.

• Access to the roof should be through internal access such as a staircase or ladder.

• All fall protection systems must be checked annually.

• Edge protection and personnel safety must be in place during the installation of any roofing processes.

Regulations

Access and Fire Risk - Access

- Fire Risk The green roofs must have fire prevention measures. Dry vegetation on green roofs does have the potential to catch alight. Although there are no mandatory fire standards for green roofs at present, the following is recommended to reduce risk: • Vegetation barriers (intentionally un-vegetated strips) of gravels/stones (20mm 40mm) or paving (concrete) at 500mm wide to all roof penetrations.

• Vegetation barriers are kept clear of encroaching plants by routine maintenance.

• Extensive roofs are unlikely to be ignited by sparks provided that the substrate base is a minimum of 30mm and contains no more than 20% organic content by volume.

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

29

III

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Firebreaks • Where required Firebreaks shall be installed to provide a minimum 6-ft wide (1.8m) continuous border.

Fire Protection • An Area Divider shall be used to partition the roof area into sections not exceeding 1,450 m², with each section having no dimension greater than 39m.

Regulations

Slope • This Design Standard is limited to roof slope designs up to 2:12. For slopes greater than 2:12.

• The roof should be sloped to shed water effectively or provide a minimum slope requirement, e.g., 1/4 inch.

Border Zone • A minimum of 1m wide continuous border free of vegetation and Growing Media.

• For design and installation purposes, the roof surface is divided into the following areas:

III

o Corners: The space between intersecting walls forming an angle greater than 45 degrees but less than 135 degrees. o For the outer boundary of the roof width measurement equal to the least of the following measurements; 0.1 x the building width or 0.4 x the building width.

The minimum width is 1.2m.

Wind Design • Vegetative roofs are not recommended where the design wind speed is greater than 140 mph (62 m/s). However, they can be designed with the consultation with a wind design engineer, or wind tunnel studies of the specific building and system.

30

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Protected Vegetative Roofing System • The System consists of vegetation, Growing Media, a fabric that is pervious to air and water, insulation, and includes a membrane that provides waterproofing and substrate materials installed over a structural deck which is able to support the system. Membranes are stick to the roof deck or supporting insulation.

• Regularly maintained • Have a substrate no less than 30mm.

• Made of vegetation that is grasses, succulents and/or perennials; • Have a substrate with at least 80% inorganic content by mass.

• All green roof systems should be designed to incorporate gravel fire breaks at perimeters and penetrations i.e. Rooflights, soil pipes, rainwater outlets etc. These fire breaks should be a minimum of 300mm wide and 50mm deep.

Extensive Green Roofs

Regulations

• The agreed minimal substrate thickness varies between 30mm and 80mm.

• Installed with 6 inches (152mm) of Growing Media or less; generally weigh between 13 and 30 pounds per square foot (63 and 146 Kg/ m²) and support sedums, herbs and grasses.

III Intensive Green Roofs • Installed with more than 6 inches (152mm) of Growing Media, generally weigh between 35 and 100 pounds per square foot (171 and 488 Kg/ m²) and support greater plant diversity.

Semi-Intensive Green Roofs • Semi-intensive roofs have a mixture of extensive and intensive systems; generally weigh between 25 and 40 pounds per square foot (122 and 195 Kg/ m²) and support plantings seen on both extension and intensive green roof installations.

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

31

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Green Roof Build-up • Substrate should have: • A depth in excess of 80 mm • A minimum depth of 80mm • A maximum of 20% organic matter • Plants such as succulents retain water within their structure, reducing the risk of drying out

Regulations

Irrigation • Extensive green roofs do not regularly require irrigation, although they are often watered during the establishment phase which is the first 4 to 6 weeks after installation.

• Semi-intensive green roofs should not need to be watered unless there is a long period which is usually defined as six weeks without rain.

• Intensive green roofs are regularly irrigated. Deeper substrates are less vulnerable to drying out as they can store more water, but the types of plants tend to be more water-dependent, so irrigation is necessary.

• One of the important ways of preventing fires is through the use of an irrigation system. The need for irrigation will differ due to climate and types of used plants.

III

Maintenance • Maintenance is needed to sustain the system and keeping vegetative roof plants healthy and to keep dry foliage to a minimum.

• Dead foliage should be removed and the moisture level of the Growing Media should be checked at regular.

• The maintenance process includes regular weeding, fertilization, and removal of dead vegetation.

32

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Standards and Design Guidelines: The following standards and guidelines shall be met in the design and construction of a green roof:

Green Roof Assembly

Gravity Loads • The applicant shall calculate green roof gravity loads following the protocol provided by the ASTM standard: “ASTM E2397.05 - Standard Practice for Determination of Dead Loads and Live Loads Associated with Green Roof Systems.”

• The density of the growing media shall be defined.

• The designer may use an un-factored, saturated density of the growing media of 2,000 kg/m3.

Design Guidelines

• A green roof assembly shall, as a minimum, consist of a root expeller system, a drainage system, a filtering layer, a growing medium and plants, and a waterproof membrane.

Slope Stability • This Design Standard is limited to roof slope designs up to 2:12.

• All roofs with slopes in excess of 10º (17%) that support green roof assemblies shall incorporate anti-shear measures.

Fire Safety • Fire resistance materials should be used and the design shall include a vegetation-free border zone and the vegetation-free border shall be equal to the vegetation height at maturity not less than 0.5m.

Waterproofing • The design and construction shall include the installation of a root barrier in all vegetated roofing systems.

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

33

III

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Drainage • A slope to drain shall be provided at the level of the waterproofing membrane.

• The system shall permit effective drainage beneath the growth media.

• Vegetation-free zones shall be provided around all drains.

• Drainage system shall be cleaned frequently.

Water Retention

Design Guidelines

• Water retention mats materials shall be employed as required to promote vegetation growth.

• The drainage layer shall be appropriate for stormwater retention and must be selected following “ASTM E2398-05 Standard Test Method for Water Capture and Media Retention of Geo-composite Drain Layers for Green Roof Systems.”

Vegetation Performance • The growing media shall be at a minimum 100mm • Un-irrigated system requires growing media at minimum 100mm.

• Used plants should survive in the local ecology.

Irrigation

III

• Adequate measures shall be provided to permit irrigation necessary to initiate and sustain the vegetation during the service life of the green roof.

Plant Selection • Vegetation on a green roof shall not include any noxious weeds.

• The plant selection and design shall be such that within three years of the planting date the selected plants shall cover no less than 80% of the vegetated roof.

• Seeds for ground cover plantings shall be spread at a rate not less than 325/m2.

• Pre-grown plugs plants shall be installed not less than 11/m2.

34

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Maintenance Plan • The applicant shall develop a maintenance plan for the green roof as per CSA-S478-95 “Guideline on Durability in Buildings” which shall define programs of routine maintenance and inspection sufficient to ensure that the green roof components perform their required functions for the duration of their design service lives.

• The maintenance plan shall address the requirements of the specified growth media and vegetation for vegetation survival.

• The maintenance plan shall address re-planting, in the event that replanting to assure that complete coverage at and maintained for the service life of the green roof.

Configuration

• The maintenance plan shall be submitted with the application for a permit for a green roof.

Configuration of a Green Roof: Root Resistant Material • Density (kg/m3) • Tensile strength (N/mm²) • Elongation to break (%)

Moisture Retention/Protection Layer • Water storage capacity (l/m²) • Thickness (mm)

III

• Weight [dry] (kg/m²) • Tensile strength (kN/m²) • Durability measure as per EU Norm

Drainage/Reservoir Layer • Water storage capacity (l/m²) • Filling volume (l/m²) • Flow rate (l/s/m²) • Weight [dry and saturated] (kg/m²) • Compressive strength (kN/m²)

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

35

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Filter Layer • Weight (kg/m²) • Tensile strength (kN/m²) • Flow rate under the hydraulic head of 10 cm (l/s/m²) • Effective pore size (m2) • Penetration force (N)

Growing Medium • Lightweight

Considerations

• Resistance to wind and water erosion • Free from weeds, diseases and pests • Fire resistance • Appropriate water retention • Good aeration at water saturation • Appropriate supply of nutrients

Green Roofs Fundamental Considerations: Location Factors • Regional and local climate • Volume of rainfall

III

• Amount of sunlight • Strength of wind

Structure Factors • Load capacity of the roof • Pitch of the roof • Shading and rain shadow from adjacent structures • Hot/cold air emissions from air conditioning units and other equipment • Height of parapet walls • Safe access to install and maintain the green roofs

36

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Vegetation • Depth of substrate required by plants • Drought tolerance of plants • Shade tolerance of planting

(Toronto Municipal Code Green Roofs)

Considerations

• Every building or addition constructed with a gross floor area of 2,000 m2 or greater shall include a green roof with a coverage of available roof space in accordance with the following chart:

Table 3: Green Roofs Codes and Standards Gross Floor Area

Coverage of Available Roof Space

(Size of Building)

(Size of Green Roof)

2,000 - 4,999 m2

20%

5,000 - 9,999 m2

30%

10,000 - 14,999 m2

40%

15,000 -19,999 m2

50%

20,000 m2 or greater

60%

III

Plant Selection • Vegetation on a green roof shall not include any noxious weeds •

The plants shall cover no less than 80% of the vegetated roof

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

37

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Considerations

Low-Rise Building: Green Roof Area Required

III

Figure 12: Low-Rise Building: Green Roof Area Required Source: (https://livingroofs.org/wp-content/uploads/2016/03/grocode/2014)

38

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Considerations

Mid-Rise Building: Green Roof Area Required

III

Figure 13: Mid-Rise Building: Green Roof Area Required Source: (https://livingroofs.org/wp-content/uploads/2016/03/grocode/2014)

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

39

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Considerations

High-Rise Building: Green Roof Area Required

III

Figure 14: High-Rise Building: Green Roof Area Required Source: (https://livingroofs.org/wp-content/uploads/2016/03/grocode/2014)

40

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

3.2 GR Types

Types

Considerations

Green roofs can be classed into three categories which are; extensive, semi-intensive, and intensive green roofs (Figure 15). Each type requires different types of vegetation and therefore a different ‘depth medium’ which pertains to the dearth of soil.

III Figure 15: Types of Green Roofs Source: (https://www.buildup.eu/en/learn/ask-the-experts/which-are-different-types-green-roofs)

Each type has different components and different considerations. Extensive green roofs are appropriate for existing structures, while semi-intensive green roof types are more likely to be used in both existing structures. Newly designed buildings depend on design and irrigation system strategies envisaged for them.

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

41

Types

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

https://www.urbangreenbluegrids.com/measures/green-roofs/intensive-green-roofs/

III Intensive Green roofs in the intensive category encompass a fully landscaped garden on the rooftop.

This type requires significant expertise and uses a different array of plants, while also not requiring significant depth in the soil. Within this system, soil depth starts from 20cm and more, which is mostly used in newer construction structures.

Trees and shrubs are typically used within these types of gardens. Intensive roofing is the least expensive amongst the three types and may include lighting, railing, and walkways.

Playgrounds, parks and vegetable gardens can also be set up within such a system.

42

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Types

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

https://www.baulinks.de/webplugin/2017/0164.php4

Semi-Intensive

III

This system is mostly adapted to a dual system, contains elements form intensive and extensive systems, ensuring both energy conservation and green diversity on a budget. It incorporates a richer, deeper substrate and waste drainage arrangements compared to extensive roofs, which will be discussed below, allowing the utilization of a more range of complex plant mixtures. In the semi-intensive green roof, vegetation requires a depth of anywhere between 13 to 20cm deep. Semi-intensive roofs are commonly utilized within extremely visible areas to improve aesthetic design using small shrubs, forbs, and grasses.

They require a higher level of maintenance compared with extensive roofs given the vegetation and substrates used.

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

43

Types

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Source: (https://odu.ro/wp-content/uploads/AcoperisVerde-extensiv-usor-extenziv-konnyu-zoldteto-4.jpg)

III

Extensive The extensive type of vegetation differs in that their roots are shallow but spread over a wider area. The greenery, which can be planted on both mats and cushions, also spreads faster as a result. Their leaves are succulent and able to store water. Sedum-mossherbaceous, moss sedum and sedum-herbaceous grass plants are used within this system.

This vegetation requires a depth of anywhere between 5 to 13cm deep. The sedum plant species are the most popular due to their shallow roots and their ability to store water.

Extensive green roofs are ideal for large houses.

44

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Types

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Figure 16: Intensive Green Roof Layers Source: (https://www.green-flat-roofs.com/images/intensive_lo_crppd.jpg)

III

Figure 17: Extensive Green Roof Layers Source: (https://odu.ro/wp-content/uploads/AcoperisVerde-extensiv-usor-extenziv/)

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

45

CHAPTER III: CHAPTER III: GREEN ROOFS GREEN ROOFS CONSTRUCTION AND ASSEMBLY CONSTRUCTION AND ASSEMBLY

Table 4: A Comparison Between Green Roof Types 3.2 Green Roof Types

Types

Green roofs can be classed into three categories which are; extensive, semiintensive, and in Green roofs can be classed into three categories which are; extensive, semi-intensive, and intensive green roofs (Figure 15). Each type requires different types of vegetation and therefore a different ‘depth medium’ which pertains to the dearth of soil.

Extensive Green Roof

Semi-Intensive Green Roof

•

Height: 6 to 20 cm

•

Height: 12 to 25 cm

•

Height: 15 cm > 1 m

•

Weight: 50 to 150 kg/m²

•

•

Weight: > 150 kg/m²

•

Vegetation: mosses, periodic flowers herbs and grasses

Weight: 120 to 200 kg/m²

•

•

Vegetation: grasses, herbs and shrubs

Vegetation: shrubs, palm trees and decorative trees

•

•

•

Soil Depth: 5 to 13 cm

Soil Depth: 13 to 20 cm

Soil Depth: 20 cm and more

•

Cost: low

•

Cost: middle

•

Cost: high

•

Maintenance: low

•

•

Maintenance: regularly

•

Irrigation: little/no irrigation

Maintenance: periodically

•

•

Irrigation: little irrigation

Irrigation: more favorable

III

Advantages: • •

Advantages:

Appropriate for large areas.

•

Appropriate for roofs that slope on a 0 to 30degree angle.

A larger variety of plants and habitats.

•

Decent insulation properties.

•

More energy efficiency and stormwater preservation ability.

•

Specific drainage systems.

•

Less technical specialized expertise is needed.

46

•

Longer membrane layer lifespan.

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Intensive Green Roof

Advantages: •

A larger variety of plants and habitats.

•

Good insulation properties.

•

It can be visually attractive.

•

Readily available, with increasingly different uses of the roofs for recreation and food cultivation.

Types

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Intensive: 1.Planting 2.Intensive soil 3.Filter 4.Beodrain

Semi-Intensive: 1.Wildflower 2.Bio-divers soil 3.Filter 4.Beodrain

III

Extensive: 1.Sedum blanket 2.Sedum substrate 3.Filter 4.Beodrain

Figure 18: Green Roof Types Components Source: (https://i.pinimg.com/73-roof-gardens-garden-products.jpg)

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

47

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

3.3 GR Systems Modular System • All the Green roof layers are contained within trays or bags that can be removed anytime • Modular systems have exposed lips, making them easier to remove

Hybrid System • Growing media and plants are contained within the tray and creates, once in place, a built-up system with no sections/separations • Hybrid systems don’t have exposed lips

Systems

Roll-Out System • Layers are laid down one after the other on the job site • Each element is supplied separately and installed layer by layer

Modular and Hybrid Systems Details The difference between Modular systems and Hybrid systems is the Modular Systems have exposed lips where Hybrid systems don’t have exposed lips (Figure 19).

III

Figure 19: Modular and Hybrid Systems Details Modified by the author, images source: (https://www.greening-solution.com/2019/Green-Roof-Trays-systems.jpg)

48

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

System

Modular System

Hybrid System

Roll-out

Lead Time

2 week

Regularly 3 months

2 week

Vegetation Coverage

Maintenance

-80% coverage after 2 years -95% minimum vegetation coverage the -Sedum mats: 90% coverage the day of the day of the installation installation No maintenance is needed

Low maintenance is needed

WaterProofing

Installation

Design

Low maintenance is needed

Any type -Quick and simple

-Quick and simple

-Simple and easy

-Each module is 500 x 500mm, H:100mm, 4 units make up 1 m2

-Each module is 500 x 500mm, H:100mm, 4 units make up 1 m2

-Total build-up depth

Less design flexibility (ex: curves, irregular angles) square design

Systems

Table 5: GR Systems

100-150mm thick

III Complete design flexibility

-This system allows -They often allow -Water and nutrient water and nutrient Plant Health water and nutrients circulation to keep healthy circulation to keep circulation plants healthy plants -Easy removal for roof repairs and trays are put Removal back in place after Not easy removal finishing the repair process Can be installed on any Low to Light slope Can be installed on any Slope slope only slope

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

49

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Layers

g

3.4 GR Layers reen roof consists of different overlaid layers (Figure 20), each layer combines with different functions. In addition, many of the layers materials used in green roof construction are manufactured from recycled building materials, which helps in reducing landfill disposal.

Figure 20: Green Roof Layers Modified by the author, images source: (http://letstalkaboutsustainablestuff.blogspot.com/2010/11/greenroof-and-its-advatages_8123.html)

Roof Deck • Made out of Concrete, Steel, or Wood • Insulation above or below the waterproofing membrane

III

Figure 21: Roof Deck Modified by the author, images source: (http://letstalkaboutsustainablestuff.blogspot.com/2010/11/greenroof-and-its-advatages_8123.html

50

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Waterproofing Membrane • Bonded/adhered • Mechanically attached • Water-resistant • Durability • Root resistance

Layers

• Rupture resistance

Figure 22: Waterproofing Membrane Modified by the author, images source: (http://letstalkaboutsustainablestuff.blogspot.com/2010/11/greenroof-and-its-advatages_8123.html)

III Types of Waterproofing Membranes • Built-up: layers of fabric and asphalt • Fluid applied • Sheets of Rubber Figure 23: Fluid Applied Rubberized Asphalt Membrane Source: (https://www.barrettroofs.com/products/black_pearl/index.html)

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

51

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Membrane Protection Layer • Protects membrane from damage

Layers

• It comes in different shapes: Boards, sheets, mats

Figure 24: Membrane Protection Layer Modified by the author, images source: (http://letstalkaboutsustainablestuff.blogspot.com/2010/11/greenroof-and-its-advatages_8123.html)

III

Types Protection Membranes • Built-up • Fluid applied • Sheets of Rubber

Figure 25: Protection Sheets Source: (https://www.nophadrain.com/product-overview/separation-protection-and-slip-layer/nd-tsf-100slip-and-protection-sheet/)

52

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Root Barrier Layer • Polyethylene sheets (minimum of 10 mm) • Prevents roots growing into or through it

Layers

• The root resistant layer can be a chemical or a physical barrier

Figure 26: Root Barrier Layer Modified by the author, images source: (http://letstalkaboutsustainablestuff.blogspot.com/2010/11/greenroof-and-its-advatages_8123.html)

Drainage Layer

III

A- Roofing Perspective • Relieves hydrostatic (liquids balance) pressure • Allows insulation to breathe B- Vegetated Roof Perspective • Prevents over-saturation of growing media • Impedes storm runoff

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

53

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Layers

Figure 27: Drainage Layer Modified by the author, images source: (http://letstalkaboutsustainablestuff.blogspot.com/2010/11/greenroof-and-its-advatages_8123.html)

Type Drainage Layer 1- Granular Layer • Gravel • Smashed Stone • Expanded Clay Aggregate • Smashed Brick

III

2- Plastic Layer • Form-Foamed Mattress • Plastic Plates Figure 28: Granular Layer

• Sometimes both granular and plastic layers are combined Figure 30: Combined Drainage All images source: (http://archigreenroof.com/greenroof-products/water-reservoir-anddrainage-board-g1/)

54

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Figure 29: Plastic Layer

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Moisture Retention Layer • Waffle boards or mats

Figure 31: Moisture Retention Layer Modified by the author, images source: (http://letstalkaboutsustainablestuff.blogspot.com/2010/11/greenroof-and-its-advatages_8123.html)

Layers

• Often integrated with drainage or protection layers

III

Figure 32: Waffle Board Source: (https://na.eventscloud.com/Greenroof_Design_and_Construction-BT)

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

55

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Filter Fabric Layer • Fabric layer is placed beneath growing media to retain fine particles

Layers

• Resistant to water pooling and rupture

Figure 33: Filter Fabric Layer Modified by the author, images source: (http://letstalkaboutsustainablestuff.blogspot.com/2010/11/greenroof-and-its-advatages_8123.html)

Growing Media Layer • Soil that contains a specified ratio of organic and inorganic material designed to provide plants with the rooting zone, air, water and nutrients that plants need to survive.

III

Figure 34: Growing Media Layer Modified by the author, images source: (http://letstalkaboutsustainablestuff.blogspot.com/2010/11/greenroof-and-its-advatages_8123.html

56

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Growing Media Requirements • Prevent over-saturation • Light-weight • Fire-resistant • Resistance to wind and water erosion • Compression resistant • Free from weeds, diseases and pests

Layers

• Has appropriate supply of nutrients

Plants Layer • This layer is the living part of the green roof system.

• The accurate selection of the plant species installed can affect the success or failure of the green roof.

• Climate: Solar radiation and air temperature, can affect the plants growing process.

III

Figure 35: Plants Layer Modified by the author, images source: (http://letstalkaboutsustainablestuff.blogspot.com/2010/11/greenroof-and-its-advatages_8123.html)

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

57

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Planting Methods • Vegetated Mats

Layers

• Pre-Planted Modules

Figure 36: Pre-Planted Modules Source: (http://optigreen.com)

Plant Irrigation • Drip or Subsurface Method

III

Figure 37: Drip System Figure 38: Subsurface System Images source: (https://www.mitre10.com.au/diy/gardening-and-green-roof/install-a-watering-system/)

58

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Planting Systems • There are several planting systems for green roofs: • Ready to Place "all-in-one" System • Pre-planted Systems (Green Roof tray and sedum mat) • Multi-Layer Systems (by inserting plant plugs or by spreading sedum cuttings)

Ready-to-Place "all-in-one" Green Roof System

• This system is easy to use, quick, requires low maintenance and suitable for all kinds of roofs.

Layers

• This modular system includes all the layers of a green roof system assembled together in one unit known as a tray or module.

Sedum Mat Pre-Planted Green Roof System • This system consists of a roll laid directly on the layer of growing medium and the used layers in this system are drain and filter.

• This system allows the roof to be vegetated directly and can be laid at any time of the season.

• They are suitable for flat roofs and roofs with pitches.

Plugs or Potted Plants of Multi-layer Green Roof System • This system can have a variety of plants on the green roof.

• The level of plant cover reaches 80% after a period of 12 to 24 months.

Images Source: (http://www.vegetalid.com/solutions/green-roofs/concepts.html)

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

59

III

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

3.5 GR Structural Design Considerations Green roofs can add loads to a roof structure (Figure 39) which are significant in comparison to usual roof design loads. The weight, stability and moisture retention characteristics of the system (mostly the growing medium and water retention mats) need to be determined.

Items to be taken into account include: • Wind Loads • Weight Loads

Green Roof as additional load on the building structure to be considered

Structural Design

• Shear Forces

III

Figure 39: Green Roofs Structural Design Modified by the author, image source: (https://livingroofs.org/people-wildlife-green-roof/)

60

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Wind Loads The need for stability of the system is increased because the negative pressure forces that can develop during high wind conditions are counteracted by the weight of the green roof system. Wind can also lead to erosion challenges on exposed sites, especially for plants in the early stages.

In addition, plant selection helps to mitigate the impact of winds. Plantings can be organized in a way where the lowest-growing and most strong species are planted in the most exposed areas. In contrast, taller plants are less wind tolerant where profitably must be installed in areas less exposed to wind.

Wind Protection In order to decrease wind exposure on the green roof, a 4 inch high metal edge along the perimeter of the green roof is recommended to protect the modules. Barriers (parapet) around the roof are often built to decrease the roof’s exposure to wind.

Structural Design

It is suggested to design vegetation-free zones filled with stone at the edges and corners of the roof where the wind pressure is high. Moreover, having barriers will decrease wind pressure on the edges of the roof area and will provide some protection against the wind flow.

Table 6: Wind Protection Specification Building Height

Parapet Height (Above Growing Media)

Vegetation Free Zone Width

Less than 46 m

150 mm

0.5 m

More than 46 m

750 mm

0.9 m

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

III

61

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Weight Loads The load-bearing capacity of a building must be recognised before planning for applying a green roof. For a green roof, the loads that the building structure must support include: • Dead Load: The final constructed weight of all built elements combined with the roof assembly, including plants, growing media and any water held in the system.

• Live Load: The weight of people using the space, and any mobile equipment that will be used occasionally on the site.

Structural Design

• Transient Load: The moving, rolling or short-term loads, including wind.

The building and roof deck must be able to support the added dead and live load of the green roof. Therefore, it is critical to consider not just the weight of plants when planted but their weight at development and maturity level, particularly where bushes and trees are proposed, as they get heavier over time. The weight of saturated plants and substrate must also be included in the load assessment.

Shear Forces It is crucial that shear forces are taken into consideration for the most part on roof pitches in excess of 10 degrees, in spite of the fact that this depends on the levels of the substrate being installed and the vegetation used. Shear forces increment with the roof slope and have to be transferred into steady beams. The substrate layer should be protected against erosion. In addition, plant choice and planting strategies are to be adjusted to the relevant slope and exposure.

III Other Structural Elements to Consider Roof Pitch: Any pitch can be planted. It decreases the chance of water entering the roof structure, allowing the use of less waterproofing and drainage layers. As a regulation, a pitch below 10 degrees is normal for green roofs, where at least drop of 1:60 can help encourage drainage.

Capacity and Space: Extensive green roofs regularly sustenance 10-25 pounds of vegetation per square foot, while intensive roofs sustenance 80-150 pounds of vegetation per square foot. In addition, extensive green roofs are suitable for low-rise lightweight structures, while heavy structures can offer support for intensive green roofs with trees.

62

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

3.6 GR Design Consideration and Components

Furthermore, designers must ascertain the physical condition of the building construction and the green roof. It is essential to know the status of the building, is it entirely a new building project or an old building. The amount of light and heat the green roofs are exposed to is also contingent on the direction of the roof. For instance, vegetation grows differently when the roof is partly shaded. Below are some of the green roofs design features considerations.

Table 7: Green Roofs Considerations Design Feature

Considerations ▪

Plant Species

▪ ▪ ▪

▪ ▪ Irrigation

▪ ▪ ▪

Access

▪

The choice of the green roof plants should consider the local ecology, accustomed to the regional climatic conditions, maintenance level, and the amount of irrigation.

Consider sun access and wind impacts on plants.

Plant diversity is important for a healthy roof.

Native plants cost less to maintain because they have evolved to survive in their right climate, the local ecology can be supported, and the green roof can be built and secured with a smaller budget.

Irrigation systems need to be installed to maintain healthy plants.

Keeping moisture to the plants provides additional cooling for the building through evapotranspiration.

Subsurface drip irrigators work best as they direct water to the plant roots without wastage.

Irrigation from rainwater harvesting, or from treated greywater is preferred.

Access to the roof should be considered for installation and maintenance purposes.

The easier the access, the cheaper to install and maintain the green roof.

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

63

Design Consideration

While designing green roofs, local climate factors must be taken into account, such as sunlight, temperature, humidity, and wind orientation. For example, in cities like Jeddah, where temperatures can exceed 40 degrees Celsius and humidity can reach 13 percent, designers must consider humidification control measures, in addition to wind direction and velocity since plants are greatly affected by wind speed and extreme temperatures.

III

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

▪ ▪ Waterproofing

▪ ▪

Green roofs can expand the life of the building’s waterproofing layer.

The soil and plants limit direct sun and wind exposure to the membrane.

The waterproofing should be tested for leaks before installing the green roof.

Installing a leak detection system with the green roof can help to locate tiny penetrations in the waterproofing layer.

Design Consideration

▪

Ensure the weight of the green roof structure is suitable for the building and not adding an extra load.

Weight ▪ The immersed weight of a green roof can vary from 90kg per m2 for a shallow system, up to 200 - 500kg per m2 for a deeper system.

Table 7: Green Roofs Considerations ▪ Wind

Accessibility

III Biodiversity

▪ ▪ ▪ ▪ ▪

Consider that the green roof needs to be accessible.

Consider green roof pathway widths and planter box depths.

Green roofs should be accessible to people with special needs such as wheelchairs.

▪ ▪ ▪

Biodiversity is vital to human and environmental health.

A green roof should support biodiversity.

Incorporate the use of native plants that will survive the local climate conditions.

Consider including water features to encourage birds to use the space.

▪ ▪ Food

▪ ▪

64

Plants, furniture and other objects located on a roof space can be exposed to windier conditions than at ground level.

Green roof design should minimize wind uplift.

Planters, furniture and shading structures need to be designed to resist windy conditions.

Growing your own food will provide a source of organic food and personal satisfaction for the grower.

The minimum soil depth should be 300-400mm to ensure healthy growth, and an integrated irrigation system is important.

Native food plants and plants with shallow rooting systems can do well on green roofs.

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Noise

Privacy

▪ ▪

Green roofs reduce noise impacts on a building.

The space should be designed to minimize noise impacts on neighbors.

▪

While designing green roofs, be careful not to interrupt others’ privacy.

Roof tops that ignore other private spaces may require privacy elements to be installed such as screens or setbacks.

▪

If the green roof is designed to be used as an open space, it is needed to apply safety measures in place.

▪ Barriers must be provided along the side of any roof to which Safety public access is provided.

Table 7: Green Roofs ▪ IfConsiderations the green roof is not trafficable, it is still required to apply a safety system to allow for the safe maintenance of the green roof.

▪ ▪ Slope

▪

▪ ▪ Soil ▪ ▪ ▪ Sun and Wind Access

▪ ▪

A green roof requires a slope of at least 2° for proper drainage.

In case the roof is completely flat, layers can be incorporated to improve drainage on the roof.

Green roofs can be installed on roofs of pitches up to 45°, yet green roofs over 10-15° may require additional support to keep soil and plants evenly distributed on the roof.

Soil for green roofs needs to be lightweight and deliver enough support for plants to grow and drain water effectively.

Once the soil is planted, a thick layer of protection (75mm) should be added to prevent soil blowing away and to reduce irrigation requirements.

In order to keep the soil healthy, fertilizers must be added to the green roof soil.

Considering the site aspect will help the green roof to flourish.

Select plants that flourish in the particular sun and wind conditions of the selected site.

The higher the roof, the greater the possible wind and sun impact.

If the purpose is to grow food on the green roof, using the maximizing daily sun exposure is important.

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

65

Design Consideration

▪

III

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Roof Environment

Design Consideration

Sound Insulation

▪ ▪ ▪

Consider some vegetation-free zones.

Add shade-tolerant plants in shade environments.

Design water access to the roof for irrigation purposes.

▪

Soil in green roofs reduces low-frequency noise, and plants reduce high-frequency noise.

For best results the soil media depth needs to be a minimum of 300mm.

Use densely planted plants to insulate the building from outside noise.

▪ ▪

▪

It is the space left around the border of the green roof and around rooftop equipment without vegetation and usually filled with stone or pavers.

Table 7: Green Roofs Considerations Vegetation ▪ Usually it is between 12” and 24” wide.

Free Zones ▪ They are recommended to ease the visual examination and limit the growth of the vegetation into the drains.

▪ ▪ Solar Panels ▪

Solar panels can be combined with green roofs.

Green roofs keep ambient temperatures at an optimal level for solar panel efficiency.

Use low growing plants which will not overshadow the solar panels.

III

66

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Roof Slope

Roof Slope

A sloped green roof (Figure 40) is a vegetated roof installed with slopes exceeding 20° and up to 35°. This structure is safely accessible and can be filled with growing medium elements. The plant selection needs to be adjusted to the extreme conditions of sloped green roofs, where the solar radiation is the highest on the area facing the sun and the water runoff is much quicker compared to a flat roof. The irrigation system must be taken into consideration and be arranged, even if it is only needed in times of drought. Including a shear barrier is necessary to provide stability.

Figure 40: Sloped Green Roof Source: (https://www.urbangreenbluegrids.com/measures/green-roofs/sloping-green-roofs/)

Basic components of a sloped green roof are similar to the flat system, taking into consideration the water management, erosion control, drainage mat and maintenance.

III 1. Vegetation Mat 2. Extensive Substrate 3. Anti-slip System 4. Drainage Mat 5. Protection and Storage Mat

Figure 41: Sloped Green Roof Basic Components Source: (https://www.urbangreenbluegrids.com/measures/green-roofs/sloping-green-roofs/)

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

67

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

The following are some considerations for a green roof with a slope: 1. Make sure the roof will stay in place • The most essential component of any sloped green roof is the confinement system, which keeps the growth medium in place during the roof’s early stages of development. If this system is not properly secured, a sloped green roof can wear down and slip under heavy rain, extreme irrigation, or poor plant growth. This is particularly for roofs with a slope greater than 2:12. If the slope above 2:12, a holding layer is needed in place to prevent the slippage of the growth medium.

Roof Slope

• Cellular confinement systems are installed on top of the drainage mat and include adaptable open cells into which the growth medium is placed. The result could be a completely supported growth medium up to eight inches in height.

• Geo-textile plastic netting materials are implanted within the growth medium. This material, which is not thicker than an inch, is sandwiched between two layers of soil.

As the roots grow, they end up weaving within the thin netting material, creating a steady cover.

2. Pay attention to peaks and valleys

III

• Irrigation can be difficult with sloped systems because the water tends to run down from the roof quickly. Consider that there is not a lot of organics within the soil layer, so the plants have only a few moments to soak up the water and as a result, vegetation near the top of the roof are not getting enough moisture, while plants near the bottom often get too much moisture as the water ponds and pools. Plant waterloving vegetation at the bottom of the green roof and less irrigation needed vegetation at the top of the slope.

• Consider installing a thicker growth medium layer near the top of the slope which is going to dry out first. Install a moisture-retention mat beneath the soil layer to assure that the vegetation layer has more time to nourish.

3. Specify a high-performance waterproofing membrane • Don’t think that just because the roof is sloped, the water is not going to pool.

Therefore, a waterproofing membrane needs to be used.

68

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Slope Applications: • A 2% roof slope (1/4:12) is the minimum recommended slope for green roofs (International Building Code).

• A roof that is too flat can lead to water pooling and damage the plants unless the green roof system includes a drainage clearance.

• Green roofs on structures steeper than 17% (2:12) are more difficult to implement than on flat roofs but they are still possible.

As in natural environments, different plant species thrive in various sunlight amounts. In green roofs, while selecting plants, natural light intensity should be taken into consideration. Sunlight intensity and temperature can affect plants health and growth. The amount of the light that plants receive will determine their ability to produce strong stems, leaves and the ability to flower.

Sun Control

Sun Control

Controlling the amount of sunlight that is exposed to specific types of plants especially in warm, hot and sunny climates. As a result, the excess solar gain may burn some plants.

Choosing the right plants for the green roof which will survive the local ecology.

III On a sunny roof, bear in mind that the temperature on the roof is likely to be at least a couple of degrees higher than the temperature on the ground; It will also be more exposed to drying winds, and therefore the plants on a sun baked green roof either need to be very drought tolerant, or they will need an irrigation system.

In addition, in some hot zones, a shading system must be introduced if the plants have a low sun and heat tolerance. Once the type of species is determined then the color pallet can be specified. Some plants will need a shading system in order to protect them from drying.

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

69

Shading Devices

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Figure 42: Sun Exposure on Green Roofs Source: (https://www.researchgate.net/profile/Kenneth_Leitch//Green-roof-sun-exposure.png)

III

Shading Devices for GR Shade is important for some type of vegetation survival, especially in hot arid environments. Shading variations over the roof area may enhance plant diversity and sunlight can be controlled by the shading devices. Sun shading devices can block or allow the sunlight to enter the shaded area with the ability to control the entered light amount. This system can be fixed, manual or automatically moveable.

The primary objective of using the shading system is to provide thermal comfort and protect some types of plants from burning because of the sun’s solar heat. In addition to create semi-private areas in social zones.

70

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Figure 43: Examples of Green Roofs Shading Devices Modified by the author, images source: (https://www.archdaily.com/27147/green-roofs-for-melbourne-11architects? Navigation)

The shading system can be used for several purposes: shade a specific type of plants, shade seating and activities zone, it could be combined with PV panels as well as combined with irrigation system (Figure 44 and Figure 45). The shading percentage is dependent on the type of used plants and the amount of seating and activities zones.

Figure 44: Solar System Acting as s Shading Element Modified by the author, image source: (https://blog.spiritenergy.co.uk/homeowner/green-roof)

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

71

Shading Devices

In order to design the shading device, it is required to understand the sun path of the place, select shading type (manual or mechanical), use standard dimensions and select the shading device material and style (Figure 43). Sometimes shading devices can be combined with other functions such as PV solar panels, source to collect rainwater or irrigation systems.

III

Shading Devices

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

III

Figure 45: Green Roof Shading System Combined with other Functions Modified by the author, image source: (https://blog.spiritenergy.co.uk/homeowner/green-roof)

Shading System Design • Effective shading can block up to 90% of sun flair and can reduce summer temperatures and improve comfort.

• A variety of shading techniques can help, from fixed or adjustable shades to trees and vegetation, depending on the building’s orientation as well as climate and latitude.

• Different designs can be implemented depending on the design concept. It could be functional (combined with other functions) or could be only aesthetic with shading purpose.

What to Shade • Shade UV sensitive plants • Shade the work area: parts of the farming zone • Shade seating's and some activities zone

72

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Integration of Solar Panels on GR A new successful trend is to integrate solar panels on green roofs (Figure 46). On roofs, both solar thermal and PV panels can be combined effectively with green roofs.

The green roof has a cooling effect and it will lower the temperature of the roof and ensure solar panel efficiency. The panels themselves must not be over-shaded by the vegetation on the green roof.

Solar Panels

In addition, it is important to realise that the area under any panels will be shaded from the sun and will not be naturally watered. The effect will be to create a different microclimate and attract different shade-loving plants. Moreover, the solar panels provide shade for the green roof below providing temporary relief from the sun’s solar heat.

III

Figure 46: Bio-Solar Green Roofs Source: (https://livingroofs.org/introduction-types-green-roof/biosolar-green-roofs-solar-green-roofs/)

Light and rain can enter beneath the solar panels ensuring good vegetation cover. Solar panels can be integrated into the green roof system without penetration of the roof membrane. Therefore, the cooling effect of a green roof can significantly improve the efficiency of the solar panel.

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

73

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

GR Lightings

Lightings

Green roofs can be just as beautiful at night time as they are in the day time (Figure 47).

Integrating lighting in a green roof system can add aesthetic feel emphasizing on plants and vegetation, planting features, pathways, activities zone and seating's area among others. Incorporating lighting within the green roof can improve safety by deterring users tripping as well as increasing pathway visibility at night. The right amount of lighting used can create a beautiful environment and a relaxing mood for entertaining at night.

Increasing the amount of time users will spend on green roofs and it has been linked to improve their overall health and well-being.

III Figure 47: Green Roof Lighting Source: (https://www.mariannemajerus.com/garden-elements-lighting-on-roof/)

Green roof lighting components can include: Power • Connect the lighting system to the main property power source or the system might get the advantage of using power from solar panels.

• Include timers, light sensor or motion sensor switches.

• Incorporate using manual and automated light switching systems.

74

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Electric Wiring • The wiring system can be channelled underground or under some elements such as gravel or stones.

Light Fixtures Location • Security lights around the pathways, seating areas and activities zone.

• In grade fixtures which are buried in-ground light fixtures with the top flush with the surface.

• Adjustable aim lighting, portable fixtures and string lighting (bulbs and LED), usage depending on the green roof users.

• Lighting fixtures to highlight plants and vegetation, planting features and water elements among others.

• Hardscape lights.

• Step lights - recessed into risers.

III

Walkways, Paths and Seating’s The usability of green roofs by people is essentially to be provided. Walkways such as pavers or cast-in-place paths encourage users movement and support the maintenance process (Figure 48 and Figure 50).

They direct and control circulation where needed. Pavers can be placed right on top of growing mediums. Examples of walkways are precast concrete pavers, natural stone, recycled plastic decking, gravel, concrete slabs and wood, among others. When planning to integrate walkways and paths on green roofs, the weight of the build-up should be considered from early design stages.

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Paths and Seating’s

• Tree lights - up and downlights.

75

Paths and Seating’s

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

During the installation of the different build-up layers, the waterproofing layer has to be secured from any damage. It is possible to install a protection mat or a drainage layer (Figure 49) which functions as a protective layer as well. The drainage of hard landscapes is usually placed on the surface.

Therefore, introducing a slight slope towards the roof drains has to be allowed to prevent water pooling since water on walkways need to be quickly drained off the surface.

III

Figure 49: Walkways and Drains on Green Roofs Source: (https://www.fastcompany.com/green-roofs-can-make-cities-healthier-and-happier-why-arentthey-everywhere)

76

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Lighting offers illumination along paths and walkways (Figure 51), helps to guide the users, highlights some design features as well as adds focus on different types of plants and vegetations.

Paths and Seating’s

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

III

Figure 51: Paths and Walkways Lighting Source: (https://zinco-greenroof.com/systems/walkways)

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

77

Paths and Seating’s

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Furnishing elements such as seats and benches on green roofs must be stable, even loaddistributing and sometimes anchored or cast in place. In addition, sun and wind factors must be taken into account. Seatings can be free-standing units or in many cases, planters edges provide seating along edges (Figure 52).

Furthermore, seatings can be placed right on top of growing medium or on paved surfaces. They can be made out of different materials such as precast concrete, natural stone, recycled plastic, recycled metal and wood, among others.

III

Figure 52: Green Roof Seating Elements Source: (https://zinco-greenroof.com/systems/seating’s)

78

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

In addition, Seating areas should not block any access or disturb circulation. Lighting fixtures could be included to offer illumination around the seating areas and help to guide the users. There are other elements that can be incorporated on green roofs. For example, water features, such as ponds, fountains and waterfalls (Figure 53) can be integrated into the green roof area considering adding their own drainage system. Furthermore, it is advisable to include separated waterproofing systems for these water features as an extra precaution to prevent leakage.

Features

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Also, railings and green screens (Figure 54) are components which can be integrated on green roofs. They can provide protection from falls during construction, as well as during normal use. They can also function as privacy screens, provide shade and be an aesthetic addition to a green roof.

III

Figure 54: Green Roofs Railings And Screens Source: (https://landscape-business.com/case-study-the-suny-esf-gateway-center-green-roof/)

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

79

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

3.7 Plant Selection

Plant Selection

The plant selection is the most distinctive component of a green roof. Designs vary to integrate different plant species and aesthetic functions. Plants selection depends on the design goals of the roof, whether they are related to function, performance, or aesthetics.

This layer needs to be carefully considered to survive the climate conditions which means considering plants that are native to semi-arid and arid areas or from a region with a similar climate.

III

Green spaces no doubt enhance social experiences. Different kinds of plants can create nature on the building, establish recreational spaces for the users and reduce the urban heat island. Plants type that is utilized for green roofs relies upon many factors, such as climate, sun exposure, water necessity, and soil condition.

By examining those factors, choosing the best plants in various climates will be easier.

Some plants can do very well in the thin soil layer and others require a more deep soil layer for growing. For more deep soil need more weight, which intends to have a more grounded structure to help the rooftop. Deeper soil can support more weight, implying that it is a means of having a stronger structure to support the roof.

Plants can control the temperature and the moistness into the building, while at the same time protecting the building from solar radiation and winds. For the most part, the solar radiation of the outside temperature and the relative humidity can be decreased as it passes through the covered planted roof.

In arid and semi-arid areas, it is essential to select low-water-use plants. In addition, there are additional aspects to consider such as wind and light. Excessive wind will increase the loose of moisture from plants as well as from the planting media itself.

Intense sunlight, light reection and heat reection from surrounding buildings will affect plant health.

It is more advisable to use local plants that are accessible and easy to get. Besides, they consume less amount of water, as they can stay longer without irrigation. The use of native plants will support the local ecology, cost less to maintain because they have evolved to survive in their right climate and can be built and secured with a smaller budget.

80

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Regardless of the desired aesthetic effect, the climate has a significant impact on plant selection for green roofs especially in hot arid climates with very little rain. Therefore, it is necessary to find plants that can stay longer without or with minimum needed irrigation (Table 8).

Name Indian Laurel

Dodonaea viscosa, Sapindaceae Hop Bush, Hopwood, shath

Image

Characteristics Origin: sub-tropical Vigor: slow-growing Humidity: semi-humid, very humid Maintenance: moderate Desiccation: vulnerable Irrigation: medium Type: shrub Height: 1 m-3 m Spread: 0.5 m-2 m Colour: pale yellow Type of fruit: drupe(fleshy/juicy) Origin: Mediterranean, sub-tropical Vigor: fast growing Humidity: very arid, semiarid, semi-humid Maintenance: moderate Desiccation: resistant Stagnant water: vulnerable Irrigation: low Type: shrub Height: 1 m-5 m Spread: 2 m-4 m Foliage: evergreen Color: light green Size: 0.3 cm Type of fruit: capsule Fruit size: 2 cm

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

81

Plant Selection

Table 8: Some of the Most Suitable Planets for Hot Arid Climates

III

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Plant Selection

Name Basil, rayhan

Image

Common Portulaca, Rose moss

III

82

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Characteristics Origin: sub-Mediterranean, Mediterranean, sub-tropical Humidity: semi-arid, semi humid Maintenance: moderate Urban climate: resistant Desiccation: resistant Stagnant water: vulnerable Irrigation: medium Type: annual, biennial, perennial Height: 0.3 m-0.6 m Spread: 0.2 m-0.4 m Foliage: deciduous Color: white, pastel yellow Size: 0.5 cm - 0.8 cm Type of fruit: nutlet Origin: sub-tropical, tropical Vigor: slow-growing Humidity: extremely arid, very arid, semiarid, semi-humid Maintenance: low Urban climate: resistant Desiccation: resistant Stagnant water: vulnerable Irrigation: low Type: annual, biennial, perennial Height: 0.1 m-0.15 m Spread: 0.2 m-0.3 m Foliage: evergreen Color: yellow, white, pink, red, violet, purple, yellow Type of fruit: capsule Fruit size: 0.6 cm

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Atriplex leucolada, Chenopodiaceae Saltbush, Orache, raghal

Image

Characteristics Origin: tropical Vigor: fast-growing Humidity: semi-arid, very humid Maintenance: high Desiccation: resistant Stagnant water: vulnerable Irrigation: low Type: annual, biennial, perennial Height: 0.6 m-0.8 m Spread: 0.4 m-0.6 m Foliage: evergreen Color: white, light green Size: 12 cm Type of fruit: capsule Fruit size: 0.2 cm

Plant Selection

Name Amaranthus tricolor, Amaranthaceae Joseph’s Coat

Origin: Mediterranean Humidity: extremely arid, very arid, semiarid Propagation: direct sowing Maintenance: low Urban climate: resistant Desiccation: resistant Stagnant water: vulnerable Irrigation: none, low Type: sub-shrub Height: 0.5 m Spread: 1 m Foliage: evergreen Color: pale green Type of fruit: capsule Fruit size: 0.6 cm

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

III

83

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Plant Selection

Name Clerodendrum inerme, Verbenaceae Indian Privet, Royal Jasmine

Image

Acacia karroo, Mimosaceae, Sweet Thorn

III

84

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Characteristics Origin: tropical Vigor: normal growth rate Humidity: semi-arid, semi-humid, Very humid Maintenance: medium to high Urban climate: resistant Desiccation: vulnerable Stagnant water: resistant Irrigation: medium to high Type: shrub Height: 1.5 m-9 m Spread: 1.5 m-3 m Foliage: evergreen Color: white Size: 10 cm Type of fruit: berry Fruit size: 0.5 cm Origin: sub-tropical, tropical Vigor: fast-growing Humidity: very arid Maintenance: low Urban climate: resistant Desiccation: resistant Stagnant water: vulnerable Irrigation: low Type: tree, shrub Height: 4 m-15 m Spread: 6 m-15 m Foliage: semi-evergreen Color: bright yellow Size: 1 cm - 2 cm Type of fruit: pod Fruit size: 4 cm - 10 cm

Name Acalypha wilkesiana, Euphorbiaceae, Copper Leaf

Alcea rosea, Malvaceae, Hollyhock

Image

Characteristics Origin: sub-tropical, tropical Vigor: fairly fast-growing Humidity: semi-arid, semi-humid, Very humid Maintenance: moderate Urban climate: vulnerable Desiccation: vulnerable Stagnant water: vulnerable Irrigation: medium Type: shrub Height: 2 m-3 m Spread: 2 m-3 m Foliage: evergreen Color: pale pink Size: 10 cm - 20 cm Type of fruit: capsule Fruit size: 0.5 cm Origin: temperate, sub-Mediterranean, Mediterranean Vigor: fast-growing Humidity: semi-arid, semi-humid Maintenance: medium to high Urban climate: resistant Desiccation: vulnerable Stagnant water: vulnerable Irrigation: medium Type: biennial, perennial Height: 0.8 m-2.2 m Spread: 0.6 m-1.2 m Foliage: deciduous Color: pink, white, violet Size: 6 cm - 10 cm Type of fruit: schizocarp

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

85

Plant Selection

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

III

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Plant Selection

Name Ornamental Asparagus

Image

Canna, Indian Shot

III

86

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Characteristics Origin: Mediterranean, sub-tropical Vigor: normal growth rate Humidity: semi-humid, very humid Maintenance: moderate Urban climate: resistant Desiccation: vulnerable Stagnant water: vulnerable Irrigation: medium Type: sub-shrub Height: 0.5 m-3 m Spread: 0.6 m-2 m Foliage: evergreen Color: white, secondary: green Smell: scented, weak, flower Type of fruit: berry Origin: sub-tropical Vigor: fairly fast growing Humidity: semi-arid, semi humid, Very humid Maintenance: medium to high Urban climate: vulnerable Desiccation : vulnerable Stagnant water: resistant Irrigation: medium to high Type: perennial Height: 1 m-1.5 m Spread: 0.5 m-0.8 m Foliage: evergreen Color: red, deep orange Size: 8 cm - 10 cm Type of fruit: capsule

Name Cape Leadwort

Image

Characteristics Origin: Mediterranean, sub-tropical, tropical Humidity: semi-humid, very humid Maintenance: moderate Urban climate: resistant Desiccation: vulnerable Stagnant water: vulnerable Irrigation: medium Type: climbers Height: 4 m-6 m Spread: 3 m-6 m Foliage: evergreen Color: light blue Size: 3 cm Type of fruit: capsule Fruit size: 0.8 cm

Plant Selection

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

*All the information is collected from Landscape Plants for Arriyadh Region, A Reference Manual.

‘This reference manual focuses on plants most well-adapted and suitable for the climate and urban environment, and helps the designers, landscape professionals, citizens in relation to their houses and private gardens’.

Source: (www.ada.gov.sa/idc/groups/public/documents/AR_ADA_Prints/006792.pdf)

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

87

III

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Criteria for Plant Options • Climate/Microclimate • Roof Function (aesthetics/energy/stormwater) • Initial Costs & Maintenance Costs • Soil Depth • Irrigation • Establishment Period • Public Use/Accessibility

Plant Selection

• Colour Palette • Native / Cultivated

Ideal Plants Characteristics • Lasting and active through the year and through the seasons • Low nutritional requirements • Low irrigation requirements • Low maintenance

III

• Lightweight at maturity • High drought tolerance especially in dry and hot weathers • Wind resistant • Non-invasive • Low and compact spreading growth • Low dry matters for fire safety concerns • Fibrous root as opposed to tap roots to protect roofing membranes • Ensure that used planters species are not disposed to pest infestation or disease • Avoid species that are toxic, poisonous, or prone to nutrient deficiency • Avoid species that are weedy or have weed potential

88

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

3.8 Installation For installing a green roof, a specialist with an understanding of the green roof system as well as general roof care and construction should be consulted. Incorrect installation may result in a variety of failures such as loss of plant life, damage to the waterproofing and slippage from the roof, among others.

Things to Consider Before Green Roof Installation 1- Calculating the bearable weight

• The usual depth for the soil layer of a green roof without any special structural design is between 4 to 6 inches.

• As the soil layer depth increases it adds more pressure on the roofs. Therefore, the roofs should be strong enough to sustain this pressure.

• If the roof structure is in doubt, the option for reinforcements should be considered.

Installation

• It is important to consider this step before the installation of green roofs to calculate the bearable weight for the roof surface.

2- Choosing an ideal location and roof surface • Green roofs are much easier to install and maintain on a flat roof surface.

• They can be installed on low-sloping roofs surfaces without the need for stabilization.

• Surfaces with an inclined slope require an extra reinforcing system such as a tray planting to hold soil in place.

Green Roof Layers Installation Order • Layer 1: Plants and Vegetation Layer • Layer 2: Growing Medium • Layer 3: Filter Layer

• Layer 5: Root Barrier • Layer 6: Insulation • Layer 7: Waterproofing Membrane • Layer 8: Roof Desk

• Layer 4: Drainage Layer

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

89

III

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Installation

How to Install a GR:

III

Green roofs can be installed by using different methods such as planting trays, creating an edged rooftop landscape area or using vegetated mats that come with plants which are developed on the ground.

Here are some few steps to install the layers on a flat surface using a protective, multilayered waterproof barrier between the soil and the roof surface: 1.

Install a rubber or plastic waterproof membrane

2.

Place a plastic sheet on the waterproof membrane layer which will function as a root barrier

3.

Place one more thin insulation layer on top of the first two layers

4.

Set a drainage mat on top of the insulation layer

5.

Add soil

6.

Set plants in place

7.

Mesh gutter guards can be installed to permit drainage to hold soil in place

8.

Adding shading system to protect plants and vegetation from the harsh climatic condition such as excessive solar radiation, dust and wind; among others. In addition, to provide thermal comfort for the roof users.

The following are essential steps which should be implemented for green roofs installation:

90

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

‘GR Installation’

1- Site preparation: Clean and prepare the roof surface by removing the loose material.

3- Place a 6mm sheet of plastic on the waterproof membrane which function as a barrier.

Figure 55: Site Preparation

Figure 57: Laying the Protection Layers

2- Install rubber or plastic waterproof membrane on top of the roof surface.

4- Install protection sheets, filter sheets and root stopping layer on the roof surface.

Figure 56: Waterproof Membrane

Figure 58: Protection Sheets, Filter Sheets and Root Stopping GREEN ROOFS CONSTRUCTION AND ASSEMBLY

91

‘GR Installation’

5- Roll out the drainage layer on the roof surface.

Figure 59: Installing The Drainage Layer

6- Add the soil layer.

Figure 60: Soil Layer

7- Applying Irrigation System: Drip System or Sprinkler System.

Figure 61: Applying Irrigation System

8- Apply the roof plants layer, there are different planting systems such as Modular System, Roll-out or Built-up.

Figure 62: Built-up System

92

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

‘GR Installation’

All the systems follow the same installation steps and the only difference is in the modular system.

9- Make sure to water the plants layer.

Figure 65: Plants Watering Step

Figure 63: Roll-out System

In the modular system, modules must be clipped to each other.

10- Adding shading system to protect plants and vegetation.

Figure 64: Modular System

Figure 66: Shading System

All images source: (https://www.instructables.com/id/Build-a-Living-Roof-Green-Roof/)

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

93

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

3.9 Maintenance

Maintenance

Maintenance is a highly important factor when considering installing green roofs. A schedule should be formulated during the design process when the demand for maintenance input can be anticipated.

Maintenance intervals can be ascertained during the design phase and include factors like micro-climate, soil types, soil depth, irrigation, type of plants used and access points. Many aspects should be considered in the maintenance process, including roof tightness. Checking that the drainage systems are not blocked is also a crucial step in maintaining green roofs. Removing unwanted weeds annually, checking water resistance, a thorough inspection of premises ceilings, irrigating plants and fertilizing the soil every nine months gives green roof longevity. Weed control, pest control, testing for fungal diseases and inspecting problems is vital for ensuring that they remain in tiptop condition.

III Figure 67: Green Roof Maintenance Source: (https://furbishco.com/wp-content/uploads/2015/07/Green-roof-maintenance.png)

• Fertilising Adding nutrients to the plants can help in enhancing their growth, flowering and resistance to weather extremes. The regularity and type of fertilisation requirement will depend on the type of green roof and its plant specification. If using non-slow release fertiliser the potential impact on the sewage system must be considered. Intensive green roofs are based on a more fertile growing medium and the planting installed will require regular fertilisation.

94

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

• Weeding Weed before the plants go to seed for most weeds this means mid-spring to summer, depending on climate conditions. Regularly, remove the weeds from the base. Pull out the entire root and put them into a container to prevent the seeds from spreading.

Watering the green roof will increase weed pressure. If the roof is watered frequently, it needs to weed more often, usually once a month. Too much watering will endorse high weed pressure. It is not recommended to use any chemical weed control products.

Unwanted plant species are best avoided by establishing a complete coverage of the desired plant species. Any wind-blown seeds or cuttings should be removed before they have the opportunity to take root.

• General Clearance Generally the removal of dead material is recommended as it allows plants the space to develop a greater coverage, improving the finished appearance of the roof. Also decreasing the risk of fungal disease forming and spreading.

Maintenance

• Plant Management

The following should be considered during design development to ensure ease of maintenance for green roofs during and after installation:

III

• Access for equipment and inspections after construction.

• Water access for irrigation purposes.

• Irrigation systems, growing media and plant selection are factors which determine long-term maintenance requirements and survival of the green roof vegetation in hot arid climates; or else, vegetation may have to be replanted and the irrigation system to be replaced.

• It is recommended to provide ease of access to the multi-functional irrigation system timers to control the time and amount of water.

• Drain system needs to be cleaned regularly. With time, the roof drain system will clog with growing medium and organic matter that migrates beneath the plant root zone. Therefore, it is essential to access the drain system for cleanout.

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

95

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

• Replanting whenever it is required.

• Provide paths and walkways to protect some vegetated areas from the impact of foot traffic.

Still, all green roofs require a minimum of two inspections per year regardless of their type. An intensive green roof requires regular maintenance depending on landscape design and planting system. In contrast, an extensive green roof needs minimal maintenance to prevent any unwanted spread of plant species.

Maintenance

Maintenance

Maintenance Schedule

III

Figure 68: Maintenance Schedule Source: (https://www.wallbarn.com/green-roofs/more-about-green-roofs/maintenance-schedule-forgreen-roof-systems/)

96

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

CHAPTER III: GREEN ROOFS CONSTRUCTION AND ASSEMBLY

Maintenance

Maintenance Schedule

III

Figure 69: Maintenance Schedule Source: (https://www.vegetalid.us)

GREEN ROOFS CONSTRUCTION AND ASSEMBLY

97

GREEN ASOCIAL SOCIAL HUB ‘‘GREENROOFS ROOFS AS AS A HUB,, 4.1 Social Life 4.2 Activity Areas 4.3 Community Gardening Space

CHAPTER IV: GREEN ROOFS AS A SOCIAL HUB

4.1 Social Life Green roofs have many benefits, as discussed in the benefits of green roofs section, and one of their benefits is the societal aspect. They are known for improving the quality of life and providing a recreational space for the users to socialize. People in buildings can enjoy in the view of their green roof as well as have a view over other lower buildings in their surroundings with roof gardens. Before explaining the potential benefits of green roofs, it is important that the lifestyle of an urbanite is understood. Urban life may appear to come with rewards, however, very often it is not without high costs. Urban life demands a high level of energy in meeting daily requirements of personal and professional life, often accompanied by stress. The green roofs social life can be an addition to an urban lifestyle that not only provides a relaxing and fun environment but can also disseminate the stress accumulated from the day, all while sharing these feelings and moments with a like-minded social circle, which in itself can have many positive mental and physical health benefits. The green roofs social life can be an addition to the urban lifestyle. Knowing that they don’t only provide a relaxing and fun environment, but can also disseminate the stress accumulated from the day. All while sharing these feelings and moments with a like-minded social circle, which in itself can have many positive mental and physical health benefits. While also, the aggregate of all the other similar applications of green roofs contributes a stronger bonded community overall.

Green roofs are known for having effects on the user’s wellbeing, help in increasing goodwill and decreasing the stress of their users by providing a more aesthetically pleasing view and a ground for social interaction. Where now there is a reason to do more than just say hello to a neighbour, but instead build the little bonds that sustain society.

GREEN ROOFS AS A SOCIAL HUB

99

CHAPTER IV: GREEN ROOFS AS A SOCIAL HUB

4.2 Activity Areas There are a lot of activities that can be enjoyed once the roof is made into an attractive place to be. These activities are limited only by imagination. Some of these activities can include things from social or solo exercising, game or cards night, movie night with a projector, dinners, or even celebrations, among others. Once the paradigm incorporates these spaces as an attractive addition, there can be an endless list of possibilities for the application of green roofs. Below are some examples of activities that can take a place on green roofs: gym, exercising zone, sports, social activities, events, celebrations, space for cinema and social farming area, among others.

Figure 70: Using Green Roofs for Different Activities Images source: (https://www.abouttimemagazine.co.uk/london/top-5-rooftop-activities-london/)

100

GREEN ROOFS AS A SOCIAL HUB

CHAPTER IV: GREEN ROOFS AS A SOCIAL HUB

4.3 Community Gardening Space One of the reasons to create green roofs is to provide attractive green spaces. As urban density increases, so does the need to grow food locally. Many communities where people are turning their rooftops into gardens for enjoyment, exercise and healthy food.

Therefore, in some parts of the world large areas of rooftops are transformed into urban farms to serve the community. The urban farming systems on green roofs are designed to optimize fruit and vegetable growth. It is a localized food system wherein the production of food occurs in the city. Moreover, green roofs can provide “farmland� for local vegetable and food production which will assist in developing a model for small scale food production. By installing green roofs with community gardening, it can enhance the value and quality of life in terms of achieving environmental, social and economic sustainability for the buildings and their users in the urban cities that will help in developing urban food systems. Green roofs provide an alternative growing space to provide fresh vegetables.

Figure 70: Using Green Roofs for Different Activities Image source: (https://www.abouttimemagazine.co.uk/london/top-5-rooftop-activities-london/)

They also provide aesthetic and physiological benefits for people in urban areas. Once green roofs are converted to produce food, they create a social atmosphere for community gardening which provide a place for social interaction. Furthermore, producing vegetables on rooftops assist in developing food security for local residents.

Users will have access to healthy and locally grown food which will improve the overall wellbeing of the community. In addition, these gardens serve to bring people together from different backgrounds. In addition, offer a medium of healthy eating.

GREEN ROOFS AS A SOCIAL HUB

101

CHAPTER IV: GREEN ROOFS AS A SOCIAL HUB

Moreover, community food production is profitable, given that urban farming on roof areas uses local resources: rainwater and filtered wastewater, solar energy and isolate the heat to reach the building. Using the rooftop to host a garden to grow your own food which the building community cultivates in some kind of common space.

Although the hot arid weather is known to have higher average temperatures, there are always ways to adapt to such condition. An example of this can be the types of vegetation that can be grown in a hot arid environment.

As for people’s comfort, in the age of ever-accelerating technology, there are solutions for many of the limitations, from vapor fans to retractable shades.

These community gardening benefits could have an effect by having people grow their own food, which in turn can be sold to other members of the community, in addition to the health benefits by having easy access in terms of proximity to the healthy food and improving overall physical health by getting exercise while tending to the garden. Furthermore, there is also a social aspect which is food brings people together, and the practice of growing food can be a community activity with a common cause that can also bring people together. This togetherness would have a positive impact on people’s state of mind and improve physical and mental health.

102

GREEN ROOFS AS A SOCIAL HUB

CHAPTER IV: GREEN ROOFS AS A SOCIAL HUB

Major Benefits of Green Roof Urban Farming 1- Environmental Sustainability • Reduce food transportation • Mitigate urban heat island • Increase biodiversity • Improve air quality • Improve urban stormwater management • Sound insulation and noise absorption

2- Social Sustainability

3- Economic Sustainability

• Active community participation

• Increase local food production and sale

• Community green space and gardens

• Increase local food security

• Social inclusion: provide fresh food to the poor

• Sell organic vegetable and food

• Education

• Access to open space

• Local employment

• Increases property value

• Space for exercise and recreation

• Reduce building cooling load and energy costs

• Aesthetic value

• Increase roof lifespan

GREEN ROOFS AS A SOCIAL HUB

103

CHAPTER IV: GREEN ROOFS AS A SOCIAL HUB

Considerations for Productive Green Roofs • The depth of the growing medium needs to be enough for securing and sustaining food plants • Waterproofing membrane needs to be protected from the used gardening tools • Fertilizations are required to provide nutrients for the used growing medium • The amount of fertilizer and irrigation depends on the requirements of the cultivated vegetable species and on local climate conditions • The use of an organic fertilizer is recommended. To minimize the impact on the runoff, avoid over-fertilizing • The drainage elements to be included • Water access for irrigation purposes • With 20cm substrate, it is suitable for fruit and vegetables such as lettuce, onions, herbs, zucchini, eggplant, squash, cabbage, melons, strawberries and such like. For vegetables and fruits such as tomatoes, green beans, raspberries, blackberries and such like a substrate depth of 28 to 40cm is recommended.

• Replanting whenever it is required • Provide paths and walkways to protect some vegetated areas from the impact of foot traffic

104

GREEN ROOFS AS A SOCIAL HUB

CHAPTER IV: GREEN ROOFS AS A SOCIAL HUB

Social Wellbeing Through Community Gardening One of the main factors or elements to take into consideration that is often overlooked is the social element. After all, we are social beings, our minds and biology are designed around it, and a lack of social interaction is often associated with negative psychological or physiological outcomes.

While urban areas have their own set of complications and issues to overcome, sometimes a basic, possibly meditative activity can provide another alternative or addition to the recreational socializing activities that take place. A small community to gather around a common cause of distressing and socializing in a positive environment from the effects of daily life, being achieved through community gardening, where localized community gardening hubs could be an attractive and efficient proposal.

Proximity is always a major factor when contemplating a type of social group activity.

By marrying community gardening with close proximity through green roofs could prove to be a contender to enhancing social life. By having a social gardening activity on the roof, the residence really provides an ideal environment in a “safe� calm and fun setting, where their new friends are always a couple of minutes away.

After looking into green roof potential for social wellbeing, this change may have a big impact when applied to large scales. For example, if people choose to utilize green roofs as social hubs, this would reduce the carbon footprint of travel to an outside location. It can provide a level of sustainability in terms of growing food in each silo community.

And of course, the aggregated effects of a more mentally healthy population.

GREEN ROOFS AS A SOCIAL HUB

105

‘‘CONCLUSION,, ‘‘CONCLUSION,, CONCLUSION GLOSSARY REFERENCES

CONCLUSION Construction of green roofs is one of the fastestgrowing areas in architecture and is becoming increasingly popular around the world. Building a green roof does not only bring economic benefits but also saves energy, filters the air among other benefits. Thus, green roof technology provides healthier air quality and reduces pollution affecting health and well-being in the urban zones. In addition, green roofs improve the thermal and acoustic insulation of buildings and provide savings of up to 70% of the energy consumed for heating and cooling of buildings.

Green roofs are a passive strategy, which insulates the building rooftop. The vegetation component of the green roof reduces the heat gain by working as an active dynamic air envelope system. It provides exterior shading to control the direct solar radiation, thus leading to considerable energy saving. It not only reduces the direct and diffuse radiation incidences on the roof but also improves the life span of the roof by modifying the temperature fluctuations experienced by its different layers, as it reduces the thermal stresses and heat gaining of roof components. Green roof implementation is essential.

With the wide range of green roofs applications, they are becoming more popular to adopt around the world. In addition, they are even suitable for commercial and industrial buildings.in addition, accessible green roofs can offer a significant value to the building’s occupants by providing a space for gathering and socializing and even a ground for food production.

Green roofs around the world became a ground for social interactions. They are known for improving the quality of life and their effect on enhancing the user’s wellbeing. Their social life can be an addition to the urban lifestyle that can provide a relaxing and fun environment which will form a bonded community overall. They provide an aesthetically pleasing view and a space for different activities.

This concept is a holistic approach that may contribute to improving the quality of life. By exploitation of such roofs, their development, and planting; a reasonable ratio of green areas can be reached in the near future. A green roof is observed to be marginally more effective in the hot arid climate and it is essential to raise awareness on this topic.

CONCLUSION

107

GLOSSARY Biodiverse Roof: Refers to a roof where either plants or seeds are introduced into the substrate making up the roof structure during construction so that they grow together.

Built-Up Roof Membrane: It is a system made up of alternate layers of tar coupled with fabrics that reinforce the bitumen to generate a crust on the top part of a building.

Carbon Footprint: The quantity of carbon (IV) oxide gas that gets emitted into the atmosphere due to human activity on individual, communal or organizational entities.

Community Gardening: It denotes a piece of land on which vegetables, fruits and other plants are grown by people using a collective approach to bring about attractive appearance.

Conventional Roof: Refers to the commonly known types of roofs made from concrete deemed to be prevalent in use in many places.

Dead Loads: Refers to the weight of a structure apart from the weight of goods, people or animals that the structure could be caused to carry.

Drainage Layer/Reservoir Board: It is a drainage stratum that stores water ad is used on green roofs to boost the capacity for water retention for supporting the vegetation that grows.

Extensive Green Roof: It is a type of green roofs characterized by variation from sedums to small grasses, flowering plants and herbs which require a temporary irrigation system and less maintenance.

Green Roof as a Recreational Space: Refers to the utilization of green roof as a place whereby refreshment can be obtained in the perspective of using a building. It is a term used when people gather on green roofs to socialize with one another.

Green Roof System: It is a roof covered partially or fully with a growing medium or vegetation that has been planted over a membrane that is waterproofed.

Growing Medium/Substrate: Refers to the substance on which plants or other growths can be grown on a green roof, usually it is known as the soil layer.

Harvesting Water: Refers to the mechanism by which catchments, runoffs and streams can be trapped to harness the water that flows.

Hot Arid Climate: It is a desert climate devoid of moisture and in which annual precipitation is scarce.

Dripping Irrigation System: It is a type of irrigation techniques that permits water to trickle slowly to the roots of specific plants that have been cultivated through valves, pipes or emitters.

Intensive Green Roof: It is a type of green roofs with a variety of vegetation like herbs and small trees and which is maintained by experts offering a proliferated potency for biodiversity and design.

It is composed of layers that offer temperature regulation through insulation.

Energy Efficiency: Refers to the aspect of using a similar quantity of energy to do a similar amount of work or to provide the same type of service without causing any energy loss.

Irrigation System: It is a plan that has been set out to provide water for plants that have been grown for a particular purpose including those on green roofs.

108

GLOSSARY

GLOSSARY Leak Detection System: It is a means for finding out the escape of materials from especially liquids like water conveyed through conduits for the purpose of making amends.

Semi-Intensive Green Roof: It is a type of green roofs which grasses, small herbs, ground covers and little herbaceous plants that which need little maintenance and intermittent irrigation.

Live Loads: Refers to the weight of goods or people on a building or in an automobile.

Semi-Arid Climate: Refers to a climate of a region whereby the level of evapotranspiration is below the threshold of the potential that can be received in the region.

Membrane Protection Layer: It is a distinct barricade which is formulated to offer protection to a membrane against the damaging forces that could originate from within or without the membrane.

Mitigation: Refers to the action of tumbling the severity of a damaging or deleterious activity.

Modular Green Roof System: Refers to a roof composed of plants and layers which give it a characteristic green color, insulation from excess heat and waterproofing characteristics.

Moisture Retention Layer: Refers to a layer instrumental in holding moisture from being lost to heat that can cause evaporation and its consequent loss.

Organic Food: Refers to cultivated food that is derived from a farming system bereft of manmade chemicals like fertilizers and pesticides.

Pre-Grown Mats: They are turf-like structures that are created from short plants especially grasses that are planted on roofs and gardens.

Root Barrier: It is an underground layer that prevents the occurrence of conflicts between hardscapes and plants that grow on green roofs.

Root barriers could occur in layers in a building and applying this layer on green roofs is to protect the roof structure.

Storm Water: Refers to the abnormal quantity of water that emanates from heavy falls of precipitation like rainfall.

Subsurface Irrigation: Refers to the unvarying application little quantities of water frequently underneath the soil surface from detached ejection lines or water sources.

Thermal Insulation: The process of preventing the transmission of heat. Green roofs offer the prevention of transmission of heat to buildings on which they are installed to ensure that there is favorable temperature.

Urban Agriculture: Refers to the practice of farming in the modern context. Green roofs are made in the context of urban agriculture because these roofs are cultivated without the sole purpose of producing food.

Urban Heat Island Effect: Refers to a situation in which an urban area or a metropolis is warmer than its surrounding areas owing to human activities. Green roofs can provide a reduction in temperature in buildings in metropolitan areas.

Wildlife Roof: It is a roof comprised of wild forms of life especially plants that are not usually domesticated. Some green roofs can be composed of wild plants.

Sedum: Refers to vastly distributed leaved plants with white, yellow, or pink flowers grown as ornaments.

GLOSSARY

109

REFERENCES Almusaed, A. (2018). Landscape Architecture: The Sense of Places, Models, and Applications. New Delhi: BoD – Books on Demand.

Alrashed, F.; Asif, M. (2015). Climatic Classification of Saudi Arabia for Building Energy Modelling. Energy Procedia. 75, 1425–1430.

Alsamawi, A., Murray, J., Gómez-Paredes, J., & Reyes, R. C. (2018). Exporting water from the desert? An analysis of the virtual water content of Saudi Arabian agricultural exports. International journal of water resources development, 34(2), 292-304.

Binabid, J. (2017). Green Facades in Arid Climate: Effects on Building Energy Consumption in Jeddah, Saudi Arabia. Illinois Institute of Technology.

Bogis, A., Bork, D., & Miller, P. (2018). Are Green Infrastructure Strategies Suitable in Arid Climates? A Design Feasibility Study from Jeddah City, Saudi Arabia.

Bradley Rowe, D. (2011). Green roofs as a means of pollution abatement, Environmental Pollution, 159. pp. 2100-2110.

Cheney C. and C. Rosenzweig. 2003. Green Roofs and Environmental Restoration Towards an Ecological Infrastructure for New York City. In Proc. Greening Rooftops for Sustainable Communities: Chicago 2003.

110

REFERENCES

Durrmeyer, Isis, Philippe Février and Xavier D’Haultfoeuille (2011). The Willingness to pay for global warming reduction: lessons from the French automobile market. Paper prepared for the Eighteenth Annual Conference of the European Association of Environmental and Resource Economists, Rome, 29 June- 2 July 2011.

D’Souza, U. (2013). The thermal performance of green roofs in a hot, humid microclimate. IWIT Trans. Ecol. Environ, 173, 475-486.

Fabricio, B.; Hewage, K. (2015). How “green” are the green roofs? Lifecycle analysis of green roof materials. Eng. Appl. Sci. 57–65.

Food and Agriculture Organization of the United Nations. (2018). Guidelines on urban and peri-urban forestry. California: Food and Agriculture Org. Guide for Vegetative (Green) Roof Systems. (n.d.). doi: 10.1520/e2777 Gómez, F., Valcuende, M., Matzarakis, A., & Cárcel, J. (2018). Design of natural elements in open spaces of cities with a Mediterranean climate, conditions for comfort and urban ecology. Environmental Science and Pollution Research, 25(26), 26643-26652.

Grant, G. (2006). Green Roofs and Façades.

New York: IHS BRE Press.

Grant, G. (2016). The Water Sensitive City.

New York: John Wiley & Sons.

Green Roof Guidelines – Guidelines for the Planning ... (n.d.).

Retrieved from https://commons.bcit.ca/greenroof/files/2019/0 1/FLL_greenroofguidelines_2018.

REFERENCES Gregoire, B.G., Clausen, J.C., 2011. Effect of a modular extensive green roof on storm water runoff and water quality. Ecol. Eng. 37, 963– 969.

Hake, A. (2007). Promoting sustainable green roofs through Leadership in Energy and Environmental Design (LEED) (Doctoral dissertation, Kansas State University).

Hansen, C. (2018, December 29). Green Roofs in MENA – Prospects and Challenges.

Retrieved from https://www.ecomena.org/green-roofs-mena/.

Henninger, S., & Moghaddam, M. A. (2019, April). Sustainable Urban Development by Expanding the Green Roofs to Improve the Urban Environment Quality (Case Study: Karaj, the fourth most populous City in Iran).

In REAL CORP 2019–IS THIS THE REAL WORLD? Perfect Smart Cities vs. Real Emotional Cities. Proceedings of 24th International Conference on Urban Planning, Regional Development and Information Society (pp. 703-711). CORP–Compentence Center of Urban and Regional Planning.

Karen Liu. (2003). Thermal performance of green roofs through field evaluation. Energy and Building.

Retrieved from www.sciencedirect.com Kind, R.J. and Wardlaw, R.L., Design of Rooftops Against Gravel Blow-Off, National Research Council of Canada, Report No. 15544, September 1976.

Köhler, M., Schmidt, M., Wilhelm Grimme, F., Laar, M., Lúcia de Assunção Paiva, V., & Tavares, S. (2002). Green roofs in temperate climates and in the hot humid tropics–far beyond the aesthetics.

Environmental management and health, 13(4), 382-391.

Li W.C., Y. K. (2014). International Journal of Sustainable Built Environment.

A comprehensive study of green roof performance from the environmental perspective, 24-44.

Lundholm, J. T., & Williams, N. S. (2015).

Effects of vegetation on green roof ecosystem services. In Green roof ecosystems (pp. 211232). Springer, Cham.

Maclvor, J.S., Lundholm, J., 2011; Blanusa et al., 2013. Performance evaluation of native plants suited to extensive green roof conditions in a maritime climate. Ecol. Eng. 37, 407–417 Madhumathi, A., Radhakrishnan, S., & Shanthipriya, R. (2016). Thermal performance evaluation of green roofs in warm humid climates: A case of residential buildings in Madurai, India. In Key Engineering Materials (Vol. 692, pp. 82-93). Trans Tech Publications.

Manning, P., van der Plas, F., Soliveres, S., Allan, E., Maestre, F. T., Mace, G. & Fischer, M. (2018).

Redefining ecosystem multifunctionality.

Nature Ecology & Evolution, 2(3), 427.

Mayrand, F., & Clergeau, P. (2018). Green roofs and green walls for biodiversity conservation: a contribution to urban connectivity? Sustainability, 10(4), 985.

REFERENCES

111

REFERENCES Muharam, A., Amer, E., & Al-Hemiddi, N. (2016). Thermal Performance of the Extensive Green Roofs in Hot Dry Climate. International Journal of Advanced Engineering Research and Science, 3(5).

Mustard, A., (2014), “Urban gardens in Cairo: the rooftop revolution”, Journal of Philanthropy Age, February 6, 2014, http://www.philanthropyage.org/2014/02/06/ro oftoprevolution/.

Pianella, A. (2018). The thermal performance of green roofs in hot and dry Mediterranean type climate (Doctoral dissertation).

Rogers, J. (2013). Green, brown or grey: green roofs as ‘sustainable’ infrastructure.

Sustainable Development and Planning VI. (Pp.323-333).

Russo, A., & Cirella, G. (2018). Modern Compact Cities: How Much Greenery Do We Need? International Journal of Environmental Research and Public Health, 15(10), 2180. doi: 10.3390/ijerph15102180.

Saeid, E. J. (2011). Effect of Green Roof in Thermal Performance of the Building an Environmental Assessment in Hot and Humid Climate (Doctoral dissertation, The British University in Dubai (BUiD)).

Santamouris, M., Ding, L., Fiorito, F., Oldfield, P., Osmond, P., Paolini, R., & Synnefa, A. (2017). Passive and active cooling for the outdoor built environment–Analysis and assessment of the cooling potential of mitigation technologies using performance data from 220 large scale projects. Solar Energy, 154, 14-33.

112

REFERENCES

Sharafi, P. (2017). Investigation of Sustainability through Green Roofs in Arid and Semi- Arid Areas. Journal of Applied Environmental and Biological Sciences.

Spri. (n.d.). ANSI/SPRI RP-14 2016 Wind Design Standard for Vegetative Roofing Systems.

Retrieved from https://www.spri.org/wpfb-file/ansi_spri-rp14-2016-wind-design-standard-for-vegetativeroofing-systems.

Stovin, V., Vesuviano, G., & De-Ville, S. (2017). Defining green roof detention performance. Urban Water Journal, 14(6), 574-588.

Tran, S., Lundholm, J. T., Staniec, M., Robinson, C. E., Smart, C. C., Voogt, J. A., & O'Carroll, D. M. (2019). Plant survival and growth on extensive green roofs: A distributed experiment in three climate regions. Ecological Engineering, 127, 494503.

Vijayaraghavan, K. (2016). Green roofs: A critical review on the role of components, benefits, limitations, and trends. Renewable and sustainable energy reviews, 57, 740-752.

Walters, S., & Midden, K. S. (2018).

Sustainability of Urban Agriculture: Vegetable Production on Green Roofs. Agriculture, 8(11), 168. doi: 10.3390/agriculture8110168.

Water Efficient Landscape and Irrigation Standards. (2016), 1–54. Retrieved from https://www.smgov.net/uploadedFiles/Depart ments/OSE/Categories/Landscape/Water_Effi cient_Landscape_Irrigation_Standards.